gimp, is not as powerfull as adobe, but you can still get fantastic results
basically is a FREE image editing software tool.........
http://www.gimp.org/
adobe photoshop CS versions are quite full on for the ameture users, i have CS4, but prefere to use the adobe elements.... far easier and user freindly, a few yrs ago i started on elements 2, now i'm on elements 7.
http://www.adobe.com/products/photoshopelwin/