Go with mod and i.c. then you have to see how your shotgun fits. Get some big piece of cardboard and put an aimpoint on it. Have it mounted on something about shoulder level. Stand 16 yards away mount the gun just like you would hunting while shooting the aimpoint. On the 2nd or third mount shoot when gun is mounted just like in hunting . Do it 3 or 4 times and see if you gun shhots where you look.
If you're in Pa there should be someplace to shoot skeet near you. Go to it and practice you'll find people who can help you out. Skeet Field is probably the single best place to learn.