are we talking analog or digital?
Analog is easy...move the dish until a picture comes in (obviously you have to have the analog box on a channel). Example is G4/G16 TP16 (Shepherd's Chapel)..When I aimed the 6 footer at G4 I tuned up TP16 and started moving the dish in the vicinity. Picture went from fuzzy to clear as I tuned it in.
Digital is harder. You have to be nuts on for a good signal. If you have an analog box the best thing to do is rough the spot with analog then fine tune it in with digital.