line up the timing marks on the crank pulley, then take the small round plate off the timing cover in front of the pump , you then put a pin in there to line it up, its someting like a 7mm pin, a drill bit will do if you are carefull and dont try rotate the engine with the pin in place or you will snap it.
if you have changed the pump without locking the timing i would check all the timing again as if you were fitting a new timing belt you may have moved the timiing belt a tooth out or something along those lines