I have to agree with Veavents, as far as software goes to use with your photographs, Photoshop is definately by far and wide the best. With all the tools the program offers, the combination of things you can do and possibilities are literally endless.
Are you having trouble with it? I know for a learner the whole thing can be quite confusing and intimidating, besides doing simple things like adding a filter, brightening the picture etc. I rejected the program for ages, until a photographer friend taught me a lot over the net, and then my art teacher taught me a lot too.
If you are having trouble, I'd recommend you look up some online Photoshop tutorials (there are tons of them), maybe see if you know anyone who could teach you a bit too? An art, design or IT teacher at school might possibly have a clue.
Don't reject digital photography books and manuals as well, they can teach you quite a bit.
Anyway, hope that helps. What exactly are you looking at doing?