Hi Don, real easy you're going to need a couple of things. A short piece of hose that you can connect to your water inlet and stick the other end into your gallon jug of antifreeze, of course the pink stuff.
You're going to turn your water valve to "winterize". Turn on your water pump.
Make sure you have drained your water heater first and have that in "by-pass" mode. if you don't you'll be wasting a lot of antifreeze filling your water heater. We usually team up to do the winterizing here, my wife turns on the faucets one at a time to allow the antifreeze to flow through each faucet, hot and cold, I make sure to change out the jugs of antifreeze as the deplete. I replace the anode rod wrapping the threads with teflon tape first.
Takes us about 30 minutes to winterize the trailer give or take.
Dan