Since the diagram is of the old-style 3-piece tarp it doesn't cover one point for the newer one-piece style. Make sure you get the thing on with the front to the front!
The front flap is the one with the straps, and it has triangular corners that fold around to the sides and cover the front of the side flaps. This keeps the wind and rain out of the sides.
The rear of the side flaps has the same corners which fold around the back.
Even the military sometimes get this wrong, I've seen many LMTVs going down the road with an inflated, flopping, tarp because it was backwards and catching the wind.
Cheers