DotNetNuke comes with quite a few modules, but it does not come with a built-in forms generator. The Helferlein Form module is a free, 3rd party module that fills that void.

It is simple, but useful. You can use it to create a form and have the form entries saved in the database and/or emailed to you or someone else. Common uses of online forms include:

Feedback Forms
Surveys
Contact Form
Sign-up Form
Suggestion Box

More...