Why not take it easy on yourself the next time you have to make a PowerPoint. Use the premade design templates to get a background and slide layout that's guaranteed to look professional. Here's how to do it in the 2010 version of PowerPoint.
Open a blank PowerPoint presentation and look for the "Design" tab at the top:
This should bring up plenty of pre-made designs with even more on a drop down menu if you click on the down arrow to the right. This will reveal over 50 templates that came with PowerPoint. To select a design template simply double click on the thumbnail of it. Also note that you can adjust the colors, fonts and effects on any of the templates. This gives you thousands of possible template combinations right in the program.
Additionally, if you don't see any design templates that you like you can select "Design Templates on Microsoft Office Online". Follow the link below to check out this website:
If you still can't find the template of your dreams you might want to consider searching the internet. A simple search for "Free PowerPoint Templates" will give you thousands if not millions of additional options to pick from.
Finally, if you just have to make your own custom background, consider following these directions to do it right:
How to Create a Template on Powerpoint: