Learn how to create an accurate affidavit letter with our free printable templates. AFFIDAVIT OF: Plaintiff. Defendant.Fill in the sponsor's full name, date of birth, and contact information. Specify the relationship to the immigrant. Making an Affidavit Form online is simple. Just answer a few questions, and Rocket Lawyer will build your document for you. In this lesson, you will learn what an affidavit is and how to format one. You'll also review a sample template that can be used to construct an affidavit.