run behinde the statue to your right as soon as u enter and wait till the guy is walking away from u then quikly run up behinde him and quik kill him then shoot the guy threw on of the cracks in the boards (hit him in the head)

sneek up on the guy on the right and kill him than look through the corner and kill the
guy in the goald.

I actually just got passed that part in the game. What you do is:

As soon as you start the mission, you press L2 on your controller so that you don't get
seen. Sneak around the outside of the barrier on the right while the gaurd is walking away
from you and then you kill him. Then you have to stand between the two barriers near the
front and shoot at the guy in the yellow and hit him in the head. The next part after that
is crazy Lol. The dude in the white is SO hard to beat! Good luck!!!

when i kill the guy at the right when hes not looking , i go kill the guy on the right
side and there is another guy not so far away and then he sees me and then i got caught!!!
im so angry i have tryed so many time's please help me and give me more informations!!! :D