Hi tanws8,
Check this example. Now please take its reference and correct your code.
Database
For this example I have used of Northwind database that you can download using the link given below.
Download Northwind Database
Namespaces
using System.Configuration;
using System.Data.SqlClient;
Controller
public class HomeController : Controller
{
    // GET: Home
    public ActionResult Index()
    {
        return View();
    }
    public JsonResult GetEmployee(int id)
    {
        string name = "";
        string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        string query = "SELECT FirstName + ' ' + LastName FROM Employees WHERE EmployeeID = @Id";
        using (SqlConnection con = new SqlConnection(conString))
        {
            SqlCommand cmd = new SqlCommand(query);
            cmd.Connection = con;
            cmd.Parameters.AddWithValue("@Id", id);
            con.Open();
            name = Convert.ToString(cmd.ExecuteScalar());
            con.Close();
        }
        return Json(name);
    }
}
View
@{
    Layout = null;
}
<!DOCTYPE html>
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
    <link href="~/style.css" rel="stylesheet" />
</head>
<body>
    <div>
        <input value="1" type="image" src="..." alt="img1" class="js-cd-panel-trigger" data-panel="main" />
        <input value="2" type="image" src="..." alt="img2" class="js-cd-panel-trigger" data-panel="main" />
        <input value="3" type="image" src="..." alt="img3" class="js-cd-panel-trigger" data-panel="main" />
    </div>
    <div class="cd-panel cd-panel--from-right js-cd-panel-main">
        <div class="sta-panel_container">
            @* Generate data from database here *@
            <div class="cd-panel__content">
                <table>
                    <tr>
                        <th>Name :</th>
                        <td><span id="lblName"></span></td>
                    </tr>
                </table>
            </div>
        </div>
    </div>
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
    <script type="text/javascript">
        (function () {
            var panelTriggers = document.getElementsByClassName('js-cd-panel-trigger');
            if (panelTriggers.length > 0) {
                for (var i = 0; i < panelTriggers.length; i++) {
                    (function (i) {
                        var panelClass = 'js-cd-panel-' + panelTriggers[i].getAttribute('data-panel'),
                            panel = document.getElementsByClassName(panelClass)[0];
                        // open panel when clicking on trigger btn
                        panelTriggers[i].addEventListener('click', function (event) {
                            event.preventDefault();
                            $.ajax({
                                type: "POST",
                                url: "/Home/GetEmployee",
                                data: "{id:" + $(this).attr('value') + "}",
                                contentType: "application/json; charset=utf-8",
                                dataType: "json",
                                success: function (response) {
                                    $('#lblName').html(response);
                                }
                            });
                            addClass(panel, 'cd-panel--is-visible');
                        });
                        //close panel when clicking on 'x' or outside the panel
                        panel.addEventListener('click', function (event) {
                            if (hasClass(event.target, 'js-cd-close') || hasClass(event.target, panelClass)) {
                                event.preventDefault();
                                removeClass(panel, 'cd-panel--is-visible');
                            }
                        });
                    })(i);
                }
            }
            function hasClass(el, className) {
                if (el.classList) return el.classList.contains(className);
                else return !!el.className.match(new RegExp('(\\s|^)' + className + '(\\s|$)'));
            }
            function addClass(el, className) {
                if (el.classList) el.classList.add(className);
                else if (!hasClass(el, className)) el.className += " " + className;
            }
            function removeClass(el, className) {
                if (el.classList) el.classList.remove(className);
                else if (hasClass(el, className)) {
                    var reg = new RegExp('(\\s|^)' + className + '(\\s|$)');
                    el.className = el.className.replace(reg, ' ');
                }
            }
        })();
    </script>
</body>
</html>
Screenshot
