You can add a watermark image to your presentation in Powerpoint 2007.

1. Open the presentation and click View.

2. Click Slide Master.

2. Under the Insert tab, within the Illustrations group, you can do one of the following:

• Click Picture, locate the picture that you wish to use for your watermark, and click Insert.
• Click Clip Art. In the Clip Art task pane, in the Search for and select a clip you’d like to use and click Go.

3. Click the Format tab then Picture Tools.

4. In the Arrange group, click Send to Back.