Yes you do have a water pump. It's turned on/off in the control panel behind the corkboard/key holder panel next to the front door. I've attached what mine looks like.
When you are dry camping, first of course put water into the gravity tank, then turn on the water pump on the panel. The water pump itself is underneath the sink behind the lower panel. They are loud so you can't miss it.
Use the pump only when feeding from the gravity tank, and keep it off when connected to city/CG water. You can screw up the pump if you run it when the gravity tank is dry or if you are connected to the city. I messed up my first trailer's pump by running it when dry. Good news is that they are easy to replace.
Make sure you don't turn on the water heater until the heater tank has water in it.
Sorry for the long winded answer.