How to add a watermark: in Word, to all pages, on one page
When you are working on a document draft or a document belonging to a particular company, you can add a watermark to specify the document's owner or its value. You can also add a watermark with your name on it to protect your intellectual property if you are working on a book or on a research project. Read this article to find out how to add a watermark to the whole document or even just some specific pages in Microsoft Office Word.
Source: ccm.net