Word 2003 insert watermark

I’m writing a test script that opens a word doc and inserts a watermark on all the pages. I have no clue what to do after this:

Tell application “finder”
open file"my file.doc" in folder"folder"
end tell

So far the document is displayed and now I need to insert a watermark from the “folder” directory. I’ve tried a for hours to apply it but have had no success.

any ideas?

Model: MacBookPro
Browser: Firefox 2.0.0.3 (Ubuntu-feisty)
Operating System: Mac OS X (10.5)