Turn off the power to the water pump. If you can locate the single fuse that works the pump, remove it. Otherwise, turn off the electricity completely.
Loosen the nut holding the cover of the pressure switch in place. Look for the switch somewhere on the well, but refer to your owner's manual if you are not sure what the switch looks like. With the cover off, look for two springs and nuts inside the switch.
Use the pliers to adjust the springs and nuts. Turn the larger spring and nut clockwise to increase the pressure and counterclockwise to reduce it. The smaller spring and nut control the timing of the pump cycle. Watch the pressure gauge on the side of the well and turn the spring counterclockwise when the pressure has reached its required level, as specified in your owner's manual.
Put the protective cover back on the switch and tighten the nut that holds the cover in place.
Turn the electricity back on.