You walk up to the white building, on the left side you will see a vertical platform.

Just before it you will see a little ledge on the ground. Run along it and jump onto the platform.

Climb up the platform and across the top of it. You will see a ledge along the side of the building.

Stay close to the side of the building and walk along it all around th building. When you get to the other side of the building you will see a platform on a 45 degree angle.

Jump onto it and go up it and then when you get to the top of it face the wall and jump onto the top railing on the platform.

Then jump onto the ledge on building then run along it to the left and then go prone and there is your sniping spot.