How to repair a cracked iphone screen?

I recently cracked the screen on my iphone 4 (out of warranty) :(
first time in years, is their an easy fix?

I was reading something on here about DIY kit, but is it easy?
http://www.crackediphonescreen.net/

I would prefer to buy my own screen and fit it, if its not too difficult

Just buy one off the iphone repair shop in Orlando (who will mail it to you) called XpressFix.http://www.1hourcellphonerepair.com