Since different machines vary slightly, be sure to read and follow posted directions! In general, here's how it works:
Step 1: Remove cap from boat's deck waste fitting.
Step 2: Insert pumpout hose nozzle into deck fitting.
Step 3: Turn pump on. If there is a hose valve, open it to start the suction.
Step 4: When no waste is seen in sight glass, close hose valve and remove nozzle from deck fitting.
Step 5: Put nozzle (with open valve) in bucket of water for 15 seconds to rinse hose. If desired, rinse boat's holding tank with water and pump dry.
Step 6: Close valve. Put away hose. Turn off pump if requested. Replace deck fitting cap.