Note - Click here for Background Colors and Graphics in PowerPoint 2007
Shortcut to Change the Background
When choosing a background color, it is important to keep in mind the color of fonts and other objects that will also be on the slide. Read the section on choosing font / background color combinations in the Changing Fonts tutorial in this series for further information.
Note - The steps in this tutorial work in all versions of PowerPoint.
Right-click on a blank area of the slide and choose Background from the shortcut menu. Alternatively, you can select Format > Background from the menu to bring up the Background Color dialog box.