It's crazy easy to do. In Word 2007, for example, just click the Page Layout tab and then click the Watermark menu. There are a slew of standard watermarks to choose from, or you can create one from custom text or an image on your computer.
If you're using an older version of Word, you can still make a watermark, but there's a lot more clicking:
- In the Format menu, click Background, and then click Printed Watermark.
- In the Printed Watermark dialog box, click Text watermark.
- In the Text box, type your watermark text.
- In the Font box, select the font style.
- In the Size box, click Auto.
- In the Color box, click Turquoise.
- Make sure that the Semitransparent check box is checked.
- Click the Diagonal option.
- Click OK.