I do not use a zappicator because I have not found one that works yet. Made a couple of them on my own that did not work either. The principle is flawed in my opinion. A pulser should work far better.
I always hold the negative / ground electrode ( green wire ) in one of my hands, away from and not touching any other part of my body. I then take the positive electrode ( red wire ) and place it near the gum line of the affected jaw ( upper jaw below the cheek bone for the sinus area ) and zap, swapping the paddles between hands on alternate cycles, always avoiding touching anywhere but the hands with the green paddle.
I have had amazing results most of the time but at least once needed the assistance of Antibiotics . Even then the zapper made things clear up much faster.