Yours is probably like ours. There is a manifold in the service bay that has a group of valves for turning off water supply to various parts of the coach. Each of these valves are marked as to where they go. There is one that is marked "Tank Fill". There is also a special wrench that is attached at the top of the manifold that can be removed to turn these valves. You will have to connect your hose to the City Water connector and turn on the water supply. Then remove the special wrench by pulling out on it and use it to turn the "Tank Fill" valve to the open position. You will hear the water begin to enter the tank. Be sure to turn off your water pump before doing this or you will have a circuit created that will cause the pump to run without doing anything.
Jim and Shirley McGehee
2004 Beaver Monterey Laguna
2013 Honda Fit Toad, 2003 Jeep Liberty Toad