Ok, so i really would like to join one of these contests that riot make, and i've noticed that the best art creations always are computer created.
I was wondering if anyone could tell me what software you use in creating awesome computer art.
(I have a windows 8 pc)

last I knew adobe was giving away creative suite 2 which includes photoshop

Photoshop is probably the best, but I don't speak from experience; I use SAI because it's easier.

Try out Sai, its free!

photoshop if you love having a ridiculous amounts of control over things (Which you likely won't use!)
Sai is MUCH more nice on memory, and can do most of art things you'd want to do in photo shop, minus the tons of photo filters (It IS photo shop after all..).

I've used photoshop and sai extensively and I can say that I prefer photoshop much more. It's level of customization is insane. Then to add on top of that you have all of photoshops features that you can use in creative ways.

Also to the OP if you plan on doing these with a mouse Illustrator might be a good option as well. Many digital artist start with a wacom bamboo tablet.Many people have false assumptions that digital art will make their art better. Don't fall under that category.

If you're too cheap to buy anything you could try Gimp, I've had some success with it and it's free.

Thanks for the feedback peeps
anyways, i'd like to download a free program, and I was looking though the ratings of some and I found that there is this program called photoscape.
anybody know about it?

here a link to it.
http://photoscape.en.softonic.com/