Hi micah,
Refer the below sample code.
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title></title>
    <!-- Bootstrap -->
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
    <script type="text/javascript" src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/js/bootstrap.min.js"></script>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" />
    <script type="text/javascript">
        $(function () {
            // Button 1 click
            $('[id*=Button1]').on('click', function () {
                var id = $(this).closest('tr').find($('[id*=ProdID]')).text();
                $.ajax({
                    type: "POST",
                    url: "CS.aspx/GetNameUserName",
                    data: '{id:"' + id + '"}',
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (response) {
                        // clear old value
                        $(".id").html('');
                        $(".imageuser").attr('src', '');
                        $(".username").html('');
                        $(".name").html('');
                        //$(".senddate").html('');
                        $(".contentpost").html('');
                        // Assign new value
                        if (response.d.length > 0) {
                            $(".id").html(response.d[0].Id);
                            $(".imageuser").attr('src', 'PROFILEPHOTOS/' + response.d[0].Imageuser);
                            $(".username").html(response.d[0].UserName);
                            $(".name").html(response.d[0].Name);
                            //$(".senddate").html(response.d[0].SendDate);
                            $(".contentpost").html(response.d[0].ContentPost);
                        }
                        $('#myModal').modal('show');
                    },
                    failure: function (response) {
                        alert(response.d);
                    },
                    error: function (response) {
                        alert(response.d);
                    }
                });
                return false;
            });
            //Save Modal details
            $("#btnSave").on("click", function () {
                var id = $('.id').html().trim();
                var name = $('.name').html().trim();
                var username = $('.username').html().trim();
                var contentPost = $('.contentpost').html().trim();
                // If you ant to insert "PROFILEPHOTOS/Test.jpg" format then use the below line
                var imageuser = $('.imageuser').attr('src').trim();
                //If you ant to insert "Test.jpg" format then use the below line
                var imageuser = $('.imageuser').attr('src').slice(($('.imageuser').attr('src').lastIndexOf('/') + 1), $('.imageuser').attr('src').length); 
                var comments = $("#comments2").val();
                $.ajax({
                    type: "POST",
                    url: "CS.aspx/InsertCommenttype",
                    data: '{id:"' + id + '",name:"' + name + '",username:"' + username + '",contentpost:"' + contentPost + '",comments:"' + comments + '",imageuser:"' + imageuser + '"}',
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (response) {
                        alert(response.d);
                        $('#myModal').modal('hide');
                        // clear value
                        $(".id").html('');
                        $(".imageuser").attr('src', '');
                        $(".username").html('');
                        $(".name").html('');
                        //$(".senddate").html('');
                        $(".contentpost").html('');
                    },
                    failure: function (response) {
                        alert(response.d);
                    },
                    error: function (response) {
                        alert(response.d);
                    }
                });
                return false;
            });
        });           
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <asp:DataList ID="dlstProducts" runat="server" RepeatColumns="3" CellSpacing="10"
        RepeatDirection="Horizontal" RepeatLayout="Table">
        <ItemTemplate>
            <table class="table table-bordered">
                <tr>
                    <td>
                        <b>ID : </b>
                        <asp:Label ID="ProdID" runat="server" Text='<%#Eval("Id") %>' /><br />
                        <b>Name : </b>
                        <asp:Label ID="lblName" runat="server" Text='<%#Eval("Name") %>' /><br />
                        <b>UserName : </b>
                        <asp:Label ID="lblUserName" runat="server" Text='<%#Eval("UserName") %>' />
                    </td>
                    <td>
                        <asp:Button ID="Button1" runat="server" Text="Show" class="btn btn-primary btn-sm" />
                    </td>
                </tr>
            </table>
        </ItemTemplate>
    </asp:DataList>
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <div class="container">
        <div class="row">
            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                <ContentTemplate>
                    <asp:Label ID="Label1" runat="server" Text=""></asp:Label><br />
                    <%--Modal 1 Start--%>
                    <div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel"
                        aria-hidden="true">
                        <div class="modal-dialog">
                            <div class="modal-content">
                                <div class="modal-header">
                                    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                                        <span aria-hidden="true">×</span></button>
                                    <h4 class="modal-title" id="H2">
                                        Pass To Followers</h4>
                                </div>
                                <div class="modal-header" style="background-color: #E8F5FD">
                                    <textarea name="comments2" rows="1" cols="20" id="comments2" class=" form-control"
                                        placeholder="Comment"></textarea>
                                </div>
                                <div id="modalbody" align="center" class="modal-body">
                                    <div class="tblCustomer">
                                        <div>
                                            <span class="pull-left " style="margin-right: 8px">
                                                <asp:Image ID="Imageuser" runat="server" ImageUrl='<%# String.Format("PROFILEPHOTOS/{0}",Eval("ImageName").ToString()) %>'
                                                    class="imageuser media-object img-rounded animated fadeInDown" Style="width: 45px;
                                                    height: 45px;" />
                                                <div class="clearfix">
                                                </div>
                                            </span>
                                            <div class="pull-left " style="">
                                                <div class="clearfix">
                                                </div>
                                            </div>
                                            <div class="pull-left " style="">
                                                <span class="name" style="font-family: Arial, Helvetica, sans-serif; font-weight: bold">
                                                    <%# Eval("Name") %></span> // <span class="username">
                                                        <%# Eval("UserName") %></span></div>
                                            <div class=" " style="">
                                            </div>
                                            <div class="clearfix">
                                            </div>
                                            <div class="" style="margin-bottom: 4px">
                                            </div>
                                            <span class="contentpost" style="font-family: Arial, Helvetica, sans-serif; font-weight: normal">
                                                <%#  Eval("ContentPost").ToString().Substring(0,180)+"...(Read More)"%></span><br />
                                            <div class="clearfix">
                                            </div>
                                            <span></span><span class="id">
                                                <%# Eval("ID") %></span>
                                        </div>
                                    </div>
                                    <div class="modal-footer">
                                        <span>
                                            <asp:LinkButton ID="btnSave" runat="server" CssClass="btn btn-info " BorderStyle="Solid"
                                                BorderWidth="1" BorderColor="#007ACC">
                                                <div class="">
                                                    <span class="" style="">
                                                        <asp:Label ID="Label28" runat="server" Text="" CssClass="glyphicon glyphicon-share-alt"
                                                            Font-Bold="True" Font-Size="Large"></asp:Label>
                                                    </span><span>
                                                        <asp:Label ID="Label29" runat="server" Text="Pass Now" Font-Bold="True" Font-Size="Large"></asp:Label>
                                                    </span>
                                                </div>
                                            </asp:LinkButton>
                                        </span>
                                    </div>
                                </div>
                            </div>
                        </div>
                    </div>
                    <%--Modal 1 End--%>
                </ContentTemplate>
            </asp:UpdatePanel>
        </div>
    </div>
    </form>
</body>
</html>
Code
protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[] { new DataColumn("Id"), new DataColumn("Name"), new DataColumn("UserName"), new DataColumn("Country") });
        dt.Rows.Add(1, "Thomas Hardy", "Mic22", "Ireland");
        dt.Rows.Add(2, "Mudassar Khan", "brown44", "India");
        dt.Rows.Add(3, "Ana Trujillo", "ana123", "France");
        dt.Rows.Add(5, "Antonio Moreno", "antonio", "Brazil");
        dlstProducts.DataSource = dt;
        dlstProducts.DataBind();
    }
}
[WebMethod]
public static List<Customer> GetNameUserName(string id)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT ID,Name,UserName,ImageName,SendDate,ContentPost FROM USERPost WHERE ID = @ID"))
        {
            cmd.Connection = con;
            cmd.CommandType = CommandType.Text;
            cmd.Parameters.AddWithValue("@ID", id);
            List<Customer> customers = new List<Customer>();
            con.Open();
            SqlDataReader sdr = cmd.ExecuteReader();
            while (sdr.Read())
            {
                customers.Add(new Customer
                {
                    Id = Convert.ToInt32(sdr["ID"]),
                    SendDate = Convert.ToDateTime(sdr["SendDate"]),
                    Name = sdr["Name"].ToString(),
                    Imageuser = sdr["ImageName"].ToString(),
                    UserName = sdr["UserName"].ToString(),
                    ContentPost = sdr["ContentPost"].ToString()
                });
            }
            con.Close();
            return customers;
        }
    }
}
[WebMethod]
public static string InsertCommenttype(string id, string name, string username, string contentpost, string comments, string imageuser)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("INSERT INTO [USERPost](ShareId,fName,UserName,FriendUserName,ShareContent,Comments,ImageName) VALUES(@ShareId,@fName,@UserName,@FriendUserName,@ShareContent,@Comments,@ImageName)"))
        {
            cmd.Connection = con;
            cmd.CommandType = CommandType.Text;
            cmd.Parameters.AddWithValue("@ShareId", id);
            cmd.Parameters.AddWithValue("@fName", name);
            cmd.Parameters.AddWithValue("@UserName", username);
            cmd.Parameters.AddWithValue("@FriendUserName", username);
            cmd.Parameters.AddWithValue("@ShareContent", contentpost);
            cmd.Parameters.AddWithValue("@Comments", comments);
            cmd.Parameters.AddWithValue("@ImageName", imageuser);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
    return "Saved";
}
public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string UserName { get; set; }
    public string Imageuser { get; set; }
    public string ContentPost { get; set; }
    public DateTime SendDate { get; set; }
}