with reference to your article

Create (Add) Watermark Text to Images (Photo) in ASP.Net using C# and VB.Net

I have uploaded an image and want to write water mark user's their own choice.

Now when i wrote inside textbox and tried to download it is showing me message that Failed-Network error.

For that purpose i wrote the following code.

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
    <br />
    <script language="javascript" type="text/javascript">
        function readURL(input) {
            if (input.files && input.files[0]) {
                var reader = new FileReader();
                reader.onload = function (e) {
                    $('#blah').attr('src', e.target.result);
                }

                reader.readAsDataURL(input.files[0]);
            }
        }
        $("#filePhoto").change(function () {
            readURL(this);
        });
    </script>
    <div class="panel panel-info">
        <div class="panel-body">
            <asp:FileUpload ID="FilePhoto" runat="server" CssClass="fileupload" onchange="readURL(this)" /><br />
            <img id="blah" src="Images/imge.png" alt="Live Preview" class="img-thumbnail" width="300"
                height="400" />
            
            <br />
            <div class="form-group has-feedback">
                <asp:TextBox ID="txtUserName" runat="server" autocomplete="off" class="validate[required] form-control"
                    placeholder="User Name">
                </asp:TextBox>
            </div>
            <asp:Button ID="btnlogin" Text="تسجیل دخول" runat="server" Class="btn btn-primary btn-block btn-flat"
                OnClick="btnlogin_Click" />
        </div>
    </div>
</asp:Content>

protected void btnlogin_Click(object sender, EventArgs e)
{
    string watermarkText = txtUserName.Text;
    
    System.Drawing.Image defaultImage = System.Drawing.Image.FromFile(Server.MapPath("~/Images/imge.png"));
 
    using (Bitmap bmp = new Bitmap(Server.MapPath("~/Images/imge.png"), false))
    {
        using (Graphics grp = Graphics.FromImage(bmp))
        {
            //Set the Color of the Watermark text.
            Brush brush = new SolidBrush(Color.Red);
 
            //Set the Font and its size.
            Font font = new System.Drawing.Font("Arial", 30, FontStyle.Bold, GraphicsUnit.Pixel);
 
            //Determine the size of the Watermark text.
            SizeF textSize = new SizeF();
            textSize = grp.MeasureString(watermarkText, font);
 
            //Position the text and draw it on the image.
            Point position = new Point((bmp.Width - ((int)textSize.Width + 10)), (bmp.Height - ((int)textSize.Height + 10)));
            grp.DrawString(watermarkText, font, brush, position);
 
            using (MemoryStream memoryStream = new MemoryStream())
            {
                //Save the Watermarked image to the MemoryStream.
                bmp.Save(memoryStream, ImageFormat.Png);
                memoryStream.Position = 0;
 
                //Start file download.
                Response.Clear();
                Response.ContentType = "image/png";
                Response.AddHeader("Content-Disposition", "attachment; filename=" + defaultImage);
 
                //Write the MemoryStream to the Response.
                memoryStream.WriteTo(Response.OutputStream);
                Response.Flush();
                Response.Close();
                Response.End();
            }
        }
    }
}

How to get solution pls.