An affidavit is a sworn statement which is "verified" by adding a formal "oath" which must be administered by a notary public. You can get this oath taken and verified at most banks for free. Note that it is the notary's verification/administration of the oath that makes your statement an "affidavit." Here's what it looks like:
Comes now John Doe, personally known to me or properly identified [by showing id] and swore and affirmed that the foregoing was true to the best of his knowledge, information and belief on this __ day of _______.