Access to the path 'C:WebSite1' is denied while downloaing and after uploading file/image file name is showing up in gridview in asp.net

Access to the path 'C:WebSite1' is denied while downloaing and after uploading file/image file name is showing up in gridview in asp.net

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>

  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

  <html xmlns="http://www.w3.org/1999/xhtml">

  <head runat="server">
    <title></title>
  </head>

  <body>

    <form id="form1" runat="server">

      <div>
        <asp:FileUpload ID="fileUpload1" runat="server" />
        <br />
        <asp:Button ID="btnUpload" runat="server" Text="Upload" onclick="btnUpload_Click" />
        <%-- <asp:GridView ID="gvDetails" CssClass="Gridview" runat="server" AutoGenerateColumns="false" DataKeyNames="FilePath">
          <HeaderStyle BackColor="#df5015" />
          <Columns>
            <asp:BoundField DataField="Id" HeaderText="Id" />
            <asp:BoundField DataField="FileName" HeaderText="FileName" />
            <asp:TemplateField HeaderText="FilePath">
              <ItemTemplate>
                <asp:LinkButton ID="lnkDownload" runat="server" Text="Download" OnClick="lnkDownload_Click"></asp:LinkButton>
              </ItemTemplate>
            </asp:TemplateField>
          </Columns>
          </asp:GridView>--%>


          <asp:GridView ID="gvDetails" runat="server" DataKeyNames="FilePath" AutoGenerateColumns="false">
            <Columns>
              <asp:BoundField DataField="Id" HeaderText="id" />
              <asp:BoundField DataField="FileName" HeaderText="Filename" />
              <asp:TemplateField HeaderText="FilePath">
                <ItemTemplate>

                  <asp:LinkButton ID="lnkDownload" runat="server" Text="download" OnClick="lnkDownload_Click"></asp:LinkButton>

                </ItemTemplate>
              </asp:TemplateField>
            </Columns>
          </asp:GridView>
      </div>
    </form>
  </body>

  </html>

   using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.Odbc;
using System.Data;
using System.Configuration;
using System.IO;
public partial class Default2 : System.Web.UI.Page

{
OdbcCoection co= new    
OdbcCoection(ConfigurationManager.CoectionStrings["demo1"].CoectionString);
protected void Page_Load(object sender, EventArgs e)
{
    if(!IsPostBack)
{

bindgridview();

}
}

private void bindgridview()
{
co.Open();
    OdbcDataAdapter da= new OdbcDataAdapter("select * from test5",co);
    DataSet ds= new DataSet();
    da.Fill(ds);
    gvDetails.DataSource= ds;
    gvDetails.DataBind();



}
//protected void Button1_Click(object sender, EventArgs e)
//{
//   // string filename = "download.pdf";
//   // System.Web.HttpResponse response = System.Web.HttpContext.Current.Response;
//   // Response.Clear();
//    //Response.ClearContent();
//    Response.ContentType="image/jpg";
//    Response.AddHeader("Content-Disposition" , "attachement; Filename=hello.pdf       ;" );
//    Response.TransmitFile(Server.MapPath("~/6028656-20160315.pdf"));
//   // Response.Flush();
//   // Response.End();

//    //Response.Write("<script>alert('Hello');</script>");



//}
protected void btnUpload_Click(object sender, EventArgs e)
{

    string filename = Path.GetFileName(fileUpload1.PostedFile.FileName);
    fileUpload1.SaveAs(Server.MapPath("Files/" + filename));

    co.Open();
    OdbcCommand cmd = new OdbcCommand("insert into test5(FileName,FilePath) values(@Name,@Path)", co);
    cmd.Parameters.AddWithValue("@Name", filename);
    cmd.Parameters.AddWithValue("@Path", "Files/" + filename);
    cmd.ExecuteNonQuery(); 
    co.Close();
    bindgridview();

    btnUpload.Attributes.Add("onclick", "document.getElementById('" + fileUpload1.ClientID + "').click();");
}


protected void lnkDownload_Click(object sender, EventArgs e)
{
    LinkButton lnkbtn = sender as LinkButton;
    GridViewRow gvrow = lnkbtn.NamingContainer as GridViewRow;
    string filePath = gvDetails.DataKeys[gvrow.RowIndex].Value.ToString();
    Response.ContentType = "image/jpg";
    Response.AddHeader("Content-Disposition", "attachment;filename=~"" + filePath + """);
    Response.TransmitFile(Server.MapPath(filePath));
    Response.End();}

i am getting this error while downloading the `file/image from the gridview