We are using a form to have potential clients fill out but I don't know where to find the information when someone fills out the information.
On their lead record in the database!
Marketo forms post directly to lead fields. There's no separate repository for form data (except the lead's Activity Log).
You can also see information on everyone that has filled out the form on the campaign or create a smart list to see who has filled out the forms. On that smart list, you can create a custom view to see all of the fields they filled out on the form.