My iPhone 4 back glass is cracked?

The back glass on my white iPhone 4 with AT&T is cracked. I want to order a DIY replacement kit off amazon but I'm not sure what I should look for. I need a kit that will come with everything that I need. I see some kits that come with a camera ring or a flash diffuser? Do I need that if its just my glass that is cracked? My camera works fine.

Just look up "cracked iPhone back replacement" It should come with the little screwdriver and the backing and I would just go on YouTube and look up how to do it or if your scared to do it I think RadioShack fixes them!