Set the page background
You can use color and pictures to create a more interesting background for your web pages. You can select a color, set a background image, or add a watermark to your page.
Not all web browsers support watermarks.
In Design view, on the File menu, click Properties.
In the Page Properties dialog box, on the Formatting tab, select the Background picture check box, and then click Browse.
Locate and click the file that contains the image you want, and then click Open.
Optional: to make the image a watermark, select the Make it a watermark check box.