There should be 4 to ??? little screws holding everything down. Some of the plastic covers will pop off or snap off but the screws hold the cooler/heatsink on and some of plastic cases too.
You will have to play around with it and see for sure that the cover pops off or it has screws holding it on. Get in to some very brite lights. Don't force anything as it might break.
I tried to find a how to thing and the closest I can get is the 560 Ti but it at least will show what you are looking for and how to do it. Good luck I hope this helps.http://www.youtube.com/watch?v=ZJG2NNGx6pw