1. Open your Excel document. Select the 'Insert' tab.
2. Click the 'Picture' icon on the ribbons bar. Search for the file or picture on your computer. A new window will appear; select the file. Select 'Insert' and the picture will appear in the document.
3. Drag and click the picture into the position you would like.
4. Double-click on the photo for the picture toolbar to appear. On the toolbar, click 'Format Picture.'
5. Select 'Watermark' under the 'Image Control/Color' tab. Lighten or darkened your watermark as necessary.