Thanks for contacting Sitefinity trial support and sorry for the delay.
Sitefinity forms development is almost identical to standard ASP.NET development in that you create usercontrols to provide this functionality in a page.
You can follow the documentation here for creating a widget: http://docs.sitefinity.com/for-developers-create-a-new-custom-widget
From that point on your should use your .net development skills to code a standard .net form within the widget and add it to the toolbox as documented.
Alternatively you can avoid development by using the inbuilt forms module: http://docs.sitefinity.com/forms
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items