What should I do? The back panel of my iPhone 4 cracked?

Sadly, today I dropped my iPhone 4 (Which I've had for roughly 2 years) and the back cracked.

When I got it I bought the Apple Care plan, but I'm pretty sure that's expired now.

So, should I buy a repair kit online? It seems fairly simple. Or, should I go to Apple? If so, what should I do then? What do you think they can do for me?

You should visit a local Apple store and see if you still have time on Apple Care. You can also check here: https://selfsolve.apple.com/...arranty.do

You can also look for sites and places that specialize in replacing iPhone Glass, you can ask at your local Apple Store for Apple Authorized repair centers.

If you do have Apple care it should only be a trip to the Apple Store or a phone call to Apple to fix.