Adding a Background to a Slide
Once a slide is prepared there are two ways to add a background
to that slide.
A background can be added directly off the Preview Window.
Right-click any slide and choose "Apply Current Background". This
will take whatever background is currently displayed in the Preview
Window and make it the background of your slide.

The second way is to use the "slide" property page.
- Right-click on the slide and choose "Slide Edit".
- Navigate to the "Slide" page.
- Click the "Background" button and locate the background you want to
add to your slide.