Hi Dave, welcome. Congrats on your gift! Unfortunately, they really don't make a manual that is rig specific like we would hope. Most things will be dealt with pretty generically. Most of the elements of a coach are similar. It's just going to be locating and figuring everything out. That might take some work.
I really recommend getting intimate with your new coach. Take tons of pictures on your phone or digital camera that you can store for reference. Take all inside pictures. Stickers, switches, layouts, everything. Then go deeper. Inside cabinets, under sofas and chairs and beds. Take out the drawers, look with a flashlight for anything hidden... components, wiring, plumbing, etc. Continue taking pictures. Remove any access panels and document what is behind them again, looking at components, electrical, and wiring. All the while, be looking and note...where is: the freshwater tank, freshwater tank drain valves, low point drain valves, hot water tank and bypass valves, water pump, 120v outlets, 12 volt outlets, the house batteries, battery disconnect switch(s), water pump switch(s), slide switch(s), etc., etc.
Look for labels on your individual appliances or units like the fridge, stove, oven, microwave, furnace, water heater, AC, etc. Then, you can search for each manual online for downloading or printing.
I would shoot out a few specific questions at a time. Googling and searching on YouTube will help give answers. In the mean time, here are some good channels on YouTube that are a good place to start your education:
https://youtu.be/WFPcV9_1frE?si=LMM6mx7kSq-nWA-X
https://youtu.be/X7scHIvjyBk?si=mGljCPH5heK2Dkk_