As bobndot said the the water tank is under the dinette seat behind the drivers seat, the gravity fill is behind a locked door on drivers side like this
Open it up and there you will find the fill spout,unscrew the cap and insert hose to fill the water tank.
To hook to city water farther back on the same side you will find the hookup just unscrew the cap and attach your hose and turn it on
If you want to empty your fresh water tank,take the seat cushion off the forward dinette seat behind the drivers seat there will be a plywood cover and a small door open it up or remove the plywood you will see a valve like this just twist it so it aligns with the pipe and the water will empty under the RV.
Any other things I can help with just ask,I have a 2006 Fleetwood Tioga 26Q
2006 TIOGA 26Q CHEVY 6.0 WORKHORSE VORTECFormer El Monte RV RentalRetired Teamster Local 692Buying A Rental Class C