Configure form widgets
You populate forms with content using form widgets. Form widgets are added on the form the same way regular widgets are added on a page. For more information, see Add widgets on pages and templates.
When you open a form to edit its content, the following list of form widgets appear on the right of the page, when you click the Content button:

After you have dragged a widget in the form, click the Edit button in the upper-right corner of the widget to configure it. Note that the Submit button widget is automatically added by the system when you drop the first widget in the form. You
Adding custom widgets to the forms toolbox
If the build-in Sitefinity CMS form widgets do not meet your requirements, you can create and use custom widgets. If you have a custom form widget that you want to use in Sitefinity CMS, you must first register the widget in the toolbox.
For more information, see Configure form widgets.