Well, it depends.... if you wrote it as a Windows app, then that's what it is... a Windows app. If you wrote it as a WebForms app, then it's a WebForm app.... you can't just take a VB.NET Windows app and "run it on the web".... the interface needs to be re-done as a webform. Now, most of the code behind the forms can be reused, but it still requires some changes.
-tg