Find the timing marks...(usually by the crankshaft pulley)...clean them up and touch them up with some white paint (whiteout is ok). Loosen up the clamp that holds the base of the distributor to the block and snug it back down so that you can just barely turn the distributor body by hand. Attach the timing light to the battery and the first spark plug wire, start the motor, pull the trigger on the timing light and aim it at the timing marks. Turn the distributor body by hand and you will see the timing mark 'move' under the timing light. Move it until it is at the timing specified for your car (check a repair manual that covers your model...available at the auto parts store for $20 - 30), tighten the bolt on the distributor base and double-check that it is still on the mark before you are done.