I never learned how to match colors. What do I do?

I know, I know - it's pathetic. I have just always worn t-shirts and jeans. I would like to start wearing chinos but I have no idea what colors go with what. The "Matching Colors" link in the sidebar just assumes that people already have this basic knowledge. And rightfully so. Is there a site or some tool that I can use to know which colors work together?