[Zope] Building feedback forms

Hello all. I'm just starting my first Zope site, and I'd like to create a feedback form for the site. I have very little "useful" experience with DTML, especially for logic. Once I create the form, how do I write a DTML script to process the input (like linking entries to variables, testing valid answers, raising errors, etc.) ANY help whatsoever would be greatly appreciated, and all the useful stuff I learn I'd like to make a how-to from. Real world solutions like this in Zope are few as far as documentation go.... thanks in advance, Eron