Unless you have source to connect up to shore power, you'll most likely need to use a jumper cable to connect from your car battery to the coach engine battery and let it charge for 5 or so minutes.
You can then start your coach engine and let it run for a while to charge up your coach/house batteries.
After house batteries are charged you can start your 120vac generator, shut off coach engine and then run on power from your generator which should charge both coach & engine batteries.
Also, I'd recommend checking the water level in all your batteries.
Good luck and let us know how it goes...