You will often find a cover over the water inlet. It keeps dirt and things from getting in when not in the water...If it is not removed, it will also keep the water out when using the boat and without water your engine will over heat.
Is the other boat a key start? If it is, have you connected the key chain to it's safety pin? The key should have a chain or spriny type cord with a plastic hook on the other end. That hook goes onto a spring loaded pin so that you don't loose the key...That pin is also a kill switch, if the key is not connected to it, the engine will not start.
itsaboat mate...Life is just a boat and then ya marry one !