A pretty good approximation of the aim for the dish is from the center of the lnb to the base of the reflector where the arm attaches.
I just want to reply back to say- I tried it and didn't seem too increase the wireless strength that I already had.
It's an off-set dish, SO, that means that IF you are aiming at a wifi signal down the block from you, you need to tilt the TOP of the dish DOWN about 24-25 degrees to aim on a horizontal plane. If not, it's actually looking "UP" 24-25 degrees higher than the signal beam.
So, the dish will be looking like it's aiming towards the ground if anything.