If you are using spring pressure – Hook you pressure source incoming usually from turbo to bottom port. You will have 2 ports to select from choose based on your best location and cap the other port. Leave one hole vented on the top and cap the other.
Electronic/Dome Pressure setup If you are using a solenoid, you will tee your input to the bottom coming from your pressure source. Output of your solenoid will go to either top port. You will cap the other top port if not being used for a dome pressure sensor.