Adding watermarks to workbook

To add a watermark, follow these steps:

   1.   On the View tab, in the Workbook Views group, click Page Layout:

   2.   Click the center section of the header:

   3.   Under Header & Footer Tools, on the Design tab, in the Header & Footer Elements group, click Picture:

   4.   In the Insert Pictures dialog box, choose the picture you want to become a watermark.

   5.   Click outside the header to see your watermark.

Notes:

• To center the image in the middle of the page, click the center section of the header and add some carriage returns before the &[Picture] code.
  You'll need to experiment to determine the number of carriage returns required to push the image into the body of the worksheet.
• If you need to adjust the image (for example, make it lighter), do the following:
  1. Click the center section of the header.
  2. Under Header & Footer Tools, on the Design tab, in the Header & Footer Elements group, click Format Picture:
     
  3. In the Format Picture dialog box, you can do additional changes:
     

See also this tip in French: Comment ajouter des filigranes au classeur.