This question came from a colleague looking to add "icons and stuff" to a Visio diagram.
I believe in applying CMS principles to your CMS designs, so use these quick four steps to create and use a background in your Visio diagrams.
|1. Right-click a tab and go to Page Setup...|
|2. Set this tab as a Background. I typically call it something like Background or my company name.|
|3. Then for each page that should use this background, also go to Page Setup...|
|4. Set the Background for your tab.|