1. If you have a laser bore sight tool, put that in/on the barrel, and superimpose the two dots at the range that you wish to be zeroed. Darker rooms are easier to do than in bright daylight at a range. then perform minor adjustments at the range until your rounds are on your target.
2. bench fire the pistol, one round. be sure to lock it in place or use sandbags to keep it steady. keeping the point of referrence with your sights and the target then have a buddy adjust the laser to align where the round impacted. you should keep looking at your point of reference. once adjusted, refire in the same manner and make minor adjustments from there. once you are satisfied, fire one last time using the laser as your point of reference. This can also be done without shooting rounds by aligning the iron sights with your target and then adjusting the laser to match. then verify at a range.
3. standing fire. fire one shot at the target through your normal sights, then with your off eye, see where that laser is pointing. with your off hand, adjust the sight left-right until aligned. then raise the laser to match the point of impact. (least accurate, and can consume rounds)