Long press on one of the 'buttons', you can change what it does and what it looks like. You'll need to download/create your own icons to put in there though. Copy them over to your SD card to a folder such as "icons", and select from there.
Had to make a theme for a freind so this is what I got so far.
Red Sox fan's will like this
This took me maybe 10 minutes so far. I already had a gde theme, thats where I borrowed the wallpaper from, The baseball battery icon was posted here a while back, and I hunted down the red sox stockings on the web resized them then added them to the updated launcher pro I had to retheme. I then did my other green theme so I didn't have to redo all my apps to match. Goind to work on a dialer for him next.
Wanted to put a bigger pic on top, but was too much for my bad vision editing. I tried a few times before I gave up and settled on this pic just behind the dial box. It still turns red when I start to type numbers in. , the one on my Moto droid turns green when I type numbers in