Do you have a budget ?
If you do try GIMP ( Gnu Image Manipulation Program ), it's completely free, if you're not used to software it will be okay for you to pick up as it will just be like learning any other program.
http://www.gimp.org/
Other free programs are Google Picas, which is meant to be easy to use and effective.
The obvious choice because it gets the most coverage is Photoshop / Photoshop Elements, the later being a cut down version of the pro one and at a fraction of the price, well worth it.
PaintShop Pro - I have no idea what this is like.
I don't know if these will do what you want but I know they're highly rated - Adobe Lightroom and Apple Aperture ( if you have a mac... ).