A family of Microsoft word processing software products for creating web, email, and print documents.
In Word 2007, you can insert a custom watermark via Page Layout tab | Watermark | Custom Watermark. When you are done, you can save the document as a template for easy reuse.
If you mean that you want to save your watermark to the gallery, do the following: After you have inserted an example watermark (in the desired format) double-click the header area to activate the header/footer view. Select the watermark. Click Page Layout | Watermark | Save Selection to Watermark Gallery.