It's good to see another avid camper who has to shut down in October!!
Here is a pretty good overview of how to winterize your water system. http://www.fiberglassrv.com/winter.html
I should mention though that when it refers to the antifreeze intake line and valve located on the intake side of your water pump, there often isn't one of these valves or any built-in provisions for getting antifreeze in. You can buy or make a hose and fitting to go on the intake side of the pump. (a used handheld shower hose has the right thread for mine, probably would work for you as well. Just cut off the end that doesn't screw onto the shower wand.) Disconnect the connection from the fresh water tank and replace with this, screwing it in hand tight plus a little bit. Stick the hose into the antifreeze jug, then run the pump to pull the antifreeze through the water lines to all the faucets. BUT, be sure to by-pass your water heater before you do this or you'll end up with all your antifreeze sitting in it.
You can also search here under winterize. quite a few discussions on various aspects you might need info on.