From: Silber Andalman Perlman Flynn <sapf@DGS.dgsys.com>

An affidavit can be set up in approximately the following way:

"After being duly sworn, the undersigned deposes and states the 
following under oath:"


	[here you should include the body of what you are saying]

Conclude with something to the affect of

"I do solemnly declare and affirm under the penalties of perjury that the 
foregoing is true and correct to the best of my knowledge, information 
and belief.  Then sign.

The format doesn't have to be exactly this way, although the language is 
important.