You cannot. Not in any sensible way.
It looks like you have no idea how ASP.NET works. I cannot help you with your confusion because I have no idea what are you missing. Probably you need to understand that APS.NET works on server side. On client side, the client gets pure HTML and does not have to have .NET, hence, you cannot speak of any forms (in the sense of
System.Window.Forms
) or any other .NET codes. Showing a form on server side would be pointless — the forms are needed for customers, but they all sit on client side.
You may want to start with very basics:
http://www.asp.net/get-started[
^].
—SA