All I did was replace the URL's for my template. For example...I made my header under PhotoStudio 5.5. Then i uploaded it to Flickr. After that, I went to the section that said Header and replaced the background URL with my new one. :) It's SO easy...but takes a little bit of trial and error.
Here's a good website to go to to get free backgrounds if you're not comfortable making them yourself: http://www.grsites.com/textures/
Here is a website where you can create your own colors for backgrounds and fonts: http://colormatch.dk/