How to create a letter template

Hi,

I'd like to create my own template for letters that are sent in envelopes with transparent address windows. The cover page will have text boxes at the proper places for the mailing address, for the sender address, and so on.

My problem is the main text body of the letter. I'd like pages to automatically append pages if a page is full. Of course, the text should begin close to the top of the page on all pages but the first. However, I can't find a way that allows me to set a different top margins for the first page than the remaining pages. Is there any way to do this?

Basically, I am trying to achieve the same thing as in the templates provided by Apple. If you create a new letter from one of those templates, you will notice that the text body has a different top margin on the first page than on remaining pages.

Thanks for your help.

Dirk