What kind of WebAssisst functionality do you wish to add to your form. Send an email? Store it to a database? add file upload? add Server Validation?
sending the form as an email can be done by adding the Create Email Message behavior to the page (WebAssist -> Create Email Message)
Storing it to a database can be done by adding the insert record behavior.
If you give more specifics on what you would like to accomplish, I can give more specifics on how it is done.