If you have pressurized water connected to the water inlet, you use city fixtures to send pressure to the inside faucets and city fill tank to fill the tank. If you don't have a pressurized water source (city water), then you attach a short piece of hose to the water inlet and immerse it into a bucket or other container of water. Then you use the water pump to suck water from the container into the water tank. Use the country fill tank setting and remember to turn the water pump on.
Attachment has full details.
UtilityCenterManual.pdf