Welcome gena to irv2
and congrats on your new to you coach
To start off you will have three tanks one a gray, sink and shower water, black for your toilet and a fresh water tank for drinking water and for flushing toilet. Water pump will pump to your sinks and to toilet for flushing.
You will have two valves large 3" or 4" for black tank a 1 1/2" from your gray tank. You will have a fresh water tank fill on side of coach on in city water intake that will divert fresh water thru a valve for filling fresh water tank. To sanitize fresh water tank use 1/4 cup of bleach and fill tank and pump water thru piping system to sinks drive coach around to mix every thing than flush with fresh water to remove bleach. Your gray an black tanks can use the blue disinfectant found at Wally-world. About 8oz for a 40 gal tank.
You will have a 6 gal hot water tank make sure you have water in it before useing for hot water. HW tank will drain off its own tank valve the large nut on face also lift relief valve at top on face of HW tank.
Both large valve openings will empty by gravity, your fresh water tank has a valve coming off its tank some where in compartment or on side of tank. Let us know how your making out and no ? is a dumb ?.