The default white page background may be the ideal blank slate for a Word document, but with a few clicks you're able to transform the entire page with a custom picture. Adding a picture through Word's "Fill Effects" menu gives you the option to match your image background to the contents within or create an entire document simply out of the background itself. Word takes care of the placement and ensures the picture is locked down behind any other text or images you add to the page.
Open Microsoft Word. To fill an existing document page, click the "File" tab, click "Open," browse to the document and double-click its file name.
Click the "Page Layout" tab. Click the "Page Color" button on the Ribbon at the top of the work area.
Click the "Fill Effects" option.
Click the "Picture" tab. Click "Select Picture."
Browse to the picture you wish to use to fill the page and double-click it. Click "OK" to close the "Fill Effects" window and return to the Word document with the page filled by the picture.