Neat looking forum.

Hope you can help. I need to code for a change of form (half dozen questions) where a user changes a select menu and then the page is reloaded with another form. Ive trawled the web and seen it done with reloaded fields or form objects but not with the form itself. Is it possible to "hold" another form somewhere? Where would the alternative form be held? What would the code be for a held form? If theres a tutorial or something somewhere then I would appreciate the URL. Failing that any clues will do.