One thing you don't want to do is pour the anti-freeze into the fresh water holding tank.
I do not have a Road Warrior, but I do own a Heartland Bighorn. I think the process would be about the same.
First open the petcock and drain the fresh water tank. That should be located near the axles on the off door side.
I your UDC, there should be two valves, one marked "water heater bypass" and one marked "winterize". Point the lever to those markings.
You should also see a hose with a plastic fitting on the end. Stick that hose into a gallon of RV anti-freeze and turn on your pump.
Then proceed open one faucet at a time till the pink stuff comes out. Do the hot and cold side. Don't forget the shower and outside shower. Be sure to have a sufficient amount in the P-traps. All of them. Flush the toilet till the pink runs out.
In short, every thing that uses water must have the pink stuff in it.
Take your compressed air and with low pressure, blow out the black tank flusher.
If you have an ice maker blow that out as well while keeping the solenoid valve open.
I may have missed something here, but someone on the forum will fill in the blanks.
Didn't your dealer go through this with you?
You can also do a search on this forum for winterization.
Peace
Dave