How to open new popup form on gridview button click ?

Step 1:

We will use ajaxtoolkit to open a new form on gridview button click or on normal button click.
You have to add reference to AjaxToolKit.dll, which you can found in the package of ajaxtoolkit from ajaxcontroltoolkit.codeplex.com.

Step 2:
You can also add Ajax tools into the asp.net toolbox, and then you can directly use its control from there, or you can hard-code.
 First, Register the DLL if you are preferring hard-code.

 <%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>


on design.aspx

<style type="text/css">

.tableBackground

{

background-color:silver;

opacity:0.7;

}

</style>

<asp:ToolkitScriptManager ID="ScriptManager1" runat="server"></asp:ToolkitScriptManager>

<asp:GridView ID="grdView" runat="server" AutoGenerateColumns="False"

onrowcommand="grdView_RowCommand">

<Columns>

<asp:TemplateField HeaderText="Emp Id">

<ItemTemplate>

<asp:Label ID="lblEmpId" runat="server" Text='<%#Eval("empId") %>'></asp:Label>

</ItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="Generate Salary">

<ItemTemplate>

<asp:LinkButton ID="btnGenerateSalary" runat="server" Text="Generate Salary" CssClass="btn btn-info" CommandArgument='<%#Eval("empId") %>'></asp:LinkButton>

</ItemTemplate>

</asp:TemplateField>

</Columns>

</asp:GridView>

<asp:Button ID="modelPopup" runat="server" style="display:none" />

<asp:ModalPopupExtender ID="ModalPopupExtender1" runat="server" TargetControlID="modelPopup" PopupControlID="updatePanel"

CancelControlID="btnCancel" BackgroundCssClass="tableBackground">

</asp:ModalPopupExtender>

<asp:Panel ID="updatePanel" runat="server" BackColor="White" style="display:none">

<div>

<span >Gross Salary</span>

<asp:Label ID="lblGrossSalary" runat="server"></asp:Label>

</div>

<asp:Button ID="btnCancel" runat="server" Text="Close" />

</asp:Panel>

The modalPopExtender will open the panel as a popup form :

on.cs

protected void grdView_RowCommand(object sender, GridViewCommandEventArgs e)

{

string empId = e.CommandArgument.ToString();

this.ModalPopupExtender1.Show();

}

//You can do any implementation here with the help of the empId, or any value that you will pass as commandargument.