I have to write a one page persuasion letter to a congress person. I would like to write it about the issues surrounding DD.

Debbie.... I don't know what topic "DD" is, so I can't help you specifically.
However this site is super in giving you a step by step guide to persuasive writing.

(Broken Link Removed)

If I can help you further with this, let me know.

In any writing, explain your acronyms or abbreviations the first time they are used.

An additional tip that I don't think is mentioned is — to be more effective — give pro agruments, con arguments and then anti-con arguments. In other words, give the reasons why you believe the changes are needed (pro), the reasons why some people do not want these changes (con), and then the counter arguments against their objections (anti-con).

Here are some other articles on persuasion that might be helpful:

http://www.members.cox.net/dagershaw/lol/Persuasion.html
http://www.members.cox.net/dagershaw/lol/Persuasion.html
http://www.members.cox.net/dagershaw/lol/InfluenceMorePrinciples.html
http://www.members.cox.net/dagershaw/lol/InfluenceStillMore.html

I hope this helps a little more. Thanks for asking.