When you have enough points, open the staircase in the room that you open the door for! While up stairs, this is the hard part, you will see a paper/broken table figure on the floor! So you go back and sprint towards it! While sprinting, you have to jump! After you’ve done that, you have to turn around and crouch down (pressing B for Xbox 360 or O for PS3)! That’s it! Last, you have to kill a whole bunch or zombies.