From your bio, I guess you are working on a 350 Chevy, or at least another V8 Chevy. If so, number 1 is the drivers side front plug. Pull all the plugs, have someone tap the starter gently as you hold your thumb over the number one hole. You will keep telling them to tap until you feel compression pushing your thumb off the hole. At the same time, be looking at your damper for the timing mark, it should be in the vicinity of the pointer. Turn it slightly to get it lined up with the zero, and you now have TDC.