I was just messing around with forms, and I can't get this question out of my head: How do you make a two-page form, like maybe Desired Username / PW on the first page and address ect on the second page? is there some sort of hidden form element to use for this? if anyone knows please let me know, thanks in advance!

One way is to use 2 separate forms.

Have the fields you want on the first form, then on your form processing page, put in a script to write these values to hidden fields within the second form.

I'm not exactly sure what you are trying to do. But, you might want to try using sessions.
http://us2.php.net/manual/en/function.session-start.php