I assume you have some icons you want to use?
If thats the case, here's what you do.
1. Open Apps Organiser, and click on the "Lables" tab.
2. Long hold on the catagory you want to change the icon for, and select "Change Icon"
3. If you're using an Icon Pack from the Market, select "Icon Pack". If its a custom icon you downloaded, or made, select "Android Image Gallery". Personally I use AndExplorer, but you'll need to get this from the market.
4. Once you've found the icon you want to use, just click it, and you're done.
Hope that helps.
Andy
P.S. Welcome to the board.