As a novice at mac and iWeb I have been search for a way to create both forms (like an application for for example) and simple tables to use. The easiest way I found was to download "Kompozer" an open source web authoring system. (http://kompozer.sourceforge.net/
Kompozer is a really easy to use program and allows you to create something i.e a form, and view the final product as you go. Then, change the view to "source" select all, copy, and paste into iweb 08 using the Html widget and hey presto 1 form ready to go.
once you get a little bit more confident you can make changes to the form using some simple html script (i.e have the form emailed to you) check out this link http://web.mac.com/will.englefield/iWeb ... Forms.html
for some more really helpful basics.
hope this proves useful to someone