I have a 2003 Cavalier LS with stock Chrome rims.
http://cgi.ebay.com/ebaymotors/2004-CHEVY-CAVALIER-LS-16-CHROME-WHEEL_W0QQcmdZViewItemQQcategoryZ43956QQihZ001QQit emZ110044938425QQrdZ1#ebayphotohosting
I wanna know if i can paint the rims and how. Do i use sand paper first and what kind of paint should i use?
Thank you in advance.

Yes you can, and you will need the right tools to do it. This is not a spray-can job.

I would, instead, reccomend you look at getting it powder coated or leaving it alone.

I heard about that but I'm kinda short on cash. If i can't spray paint it, what type of tools and paint do i need to paint the rims?

You "could" do it with something like you'll find in this thread:
http://www.automotiveforums.com/vbulletin/showthread.php?t=635534

A shit load of cleaning, degreasing, sanding, and patience will be involved.

The maxim most people use when modifying cars (at least the ones with decent cars) is this: Don't go cheap. If you want something you can't afford, save up for it. If its worth doing than its worth doing right.

...save up, get it powdercoated. Or, save up and find rims that are the right color to begin with.

I see. Thanks a lot!