You can set pattern or image to sit behind all pages in a document. For example, you can create the effect of a watermark by generating a faded image (you can use Photopaint) and then including it into the page background.
To set a page background:
Select Page Background from the Format menu
To set the background to one of the predefined patterns, click on the pattern.
To include an image of your own, click the From File checkbox and use the file browse button to pick the image.
Set the Display to Center (preserve original image/pattern size and centre it on the page), Stretch (expand or shrink the image/pattern to fit the page) or Tile (repeat the image/pattern across and down the page).
Select the Print with page background checkbox if you want the pattern or image to be printed with your document.