Firstly, welcome to GTPlanet

. You really need to provide more information when asking for suggestions. The more information you provide us, the more information we can give to you.
* What operating system are you using?
* Are you looking for free software, or do you want commercial software?
* If commercial, then how much are you willing to spend?
* What kind of "editing?" Heavy editing as in Photoshop?
* Have you searched Google?
For photo editing, I personally use The GIMP. There are many people here that use this application so you can find plenty of help if you need it.