There are 2 places to "water" your trailer.
One is a hose connection that puts water directly into your pipes and faucets.
You have apparently attached to this one.
IF you also have a fresh water storage tank then you need to look for another
fill port something like this ---
This is a gravity fill port and you need fill the tank by sticking a hose in there
and turn on the hose faucet until water runs out the fill opening.
Then you use your onboard water pump to move water from the tank to your
I use a short piece of cut off garden hose because the screw end of the
hose won't fit in there but just a hose with no end one it will fit.
(I actually use a cut off washing machine fill hose for filling my tank.)
You also probably need to turn some valves on or near your water heater to
un-bypass it and get it into summer mode BEFORE you turn it on.
The water heater MUST be filled with water before you attempt to heat it!!!!!
Water heater may have a drain plug that needs to be replaced AND the fresh
water tank may have an open drain valve.
A dealer or knowledgeable RV type neighbor or friend/co-worker would
be invaluable at this point.
I am not familiar with your rig so I can't give you specific directions but someone else
here might be able to help or you might need to take some photos and we can then
give you better directions.