lepetitsouris said:
Photoshop is probably the best (in my opinion). However, if you don't wanna pay amy money, gimp is really good; it's like a simpler form of photoshop. If you don't wanna download any programs; fotoflexer.com and picnik.com are the most common online editing programs. As for the icon size, just resize the image from whatever it was to 200x200 or 100x100. I'm not sure how to explain it because I'm unaware of what program you use.

You could also use pixlr.com. It's sort of like a really simpler form of GIMP.

I use picnik.com.

^is it free? I've been looking for an editing program too, I have three but they're all suckish. and my mom is afraid someone will hack onto our images.

I use Photofiltre, only. It's perfect for me.
I have Photoshop but SOMETIMES (I mean some functions) I can't stand it. But a lot of people like it.
Gimp is good, but it is VERY slow on my computer, have no idea why.
Gimp is free, it's an advantage.
But you can download a free version of Photoshop. It's called Portable Photoshop.