great program for color

alright, I need some help finding a program that will help me add color to my posters...
here are some of them (mind the crappiness)

Spoiler

Spoiler

You could try Adobe Illustrator or Open Canvas if you want to turn you drawings into something you might see on Deviant Art or something... You'll have to buy the real thing if you want to bypass the 30 day trial, though.