You can do this in just a few paragraphs:

1. Congratulations. Praise his policy proposals (pick one you like) and his very effective campaign.

2. Most importantly, millions of Americans, myself included, have been inspired to action by your campaign. Your ideas and attitude have provided much needed hope ......How his message of hope applies to you ---> Dream Act.

3. Your story + stats provided in the template provided by USAgirl.

4. Ask, ask, ask. Make a plea for him to support the Dream Act. Tie it back to hope if you want.

5. Thank him and sign.

That's it. Not too hard.