ASP.net 팝업 상자 정보 제출

<asp:Button ID="submit" runat="server" onclick="submit_Click" Text="submit" />
    <asp:Button ID="btnCallBack" runat="server" Text="     confirm" OnClick="btnCallBack_Click" />
    <asp:Button ID="btnHid" runat="server" OnClick="btnHid_Click" Width="0px" />
    <asp:HiddenField ID="hid" runat="server" />

    protected void submit_Click(object sender, EventArgs e)
    {
        List<object> values = Grid1.GetSelectedFieldValues(new string[] { Grid1.KeyFieldName });
        string data = "alert('Selected row key values:";
        for (int i = 0; i < values.Count; i++)
            data += @"
" + values[i].ToString();

        if (Session["strlist"] != null)
        {
            strLists = (List<String>)Session["strlist"];
            for (int i = 0; i < strLists.Count; i++)
            {
                data += @"
" + strLists[i].ToString();
            }
        }
        data += "')";
        //ClientScript.RegisterClientScriptBlock(typeof(), "test", data, true);

    }
    protected void btnCallBack_Click(object sender, EventArgs e)
    {
        //do sth
        string js = string.Format("document.getElementById('{0}').value=confirm('    ?');document.getElementById('{1}').click();", hid.ClientID, btnHid.ClientID);
        ClientScript.RegisterStartupScript(GetType(), "confirm", js, true);
    }
    protected void btnHid_Click(object sender, EventArgs e)
    {
        string result = hid.Value.ToLower() == "true" ? " " : " ";
        Response.Write(string.Format("     {0}", result));
    }