How to add a paypal payments form:

1 - create a hidden page in your sitemap called "payment".
2 - create your main form in your ProForms editor and make sure that at least the "total" question type is added.
3 - create your main form page, add the display block using your main form, and set it to forward to another page - "payment" (made in step 1).  Also be sure to set it to pass the EntryID#.
4 - create a new form in your ProForms editor called "payment" add the "paypal" payment question type to that form. Make sure you set all of your paypal settings and a return page if applicable and reference the "total" question handle from form #1.
5 - go to your "payment" page created in step 1 and add the second payment form.

That should be it.  

- page #1 with form #1 containing the total question type, set to forward to page #2
- page #2 with form #2 containing the paypal question type.