1991 fresh water pump help

[supercobra]

I bought a 91 sea ray 310 sundancer and can't get the water to come out any of the sinks or toilet.It doesn't have a switch in the shore panel area,all it has is a water heater switch. I filled up the tank and turned on the switch on the dash that says water pump and got nothing.Does it have a valve or switch in the engine bay area?If I can't get it working or the pump is bad how can I drain or force it out so it don't freeze up?It's 40 gallons.After I filled it up with water I found the dock water supply in the back under the spicket but that operates on a different system don't it?It doesn't fill up that 40 gallon water tank does it?But I still need to know how to get it drained if I can't get pump to work.Is there a way to test the pump somehow?