Where Do Form Responses Show Up

Forms will help you capture information about contacts that fill out and submit the form. In order to view this information, start by navigating to "Sites" > "Forms" (at the top of the screen) > "Submissions"  where, you will be able to filter or search through form submissions and view the information that was provided on a particular form submission. 

If you are using custom fields on your forms, those will also be shown in the Contact Details page which you can access by navigating to "Contacts" > (then search or click on any Contact).