There are a number of threads both here and under the Winnebago owners forum on winterizing. Most of the newer Winnebago's have to be air blown out as there is no hot water heater bypass to allow using the pink RV antifreeze without filling up the hot water heater. The "pink stuff" is only used for pouring into the drains at the end. But check out your owner's manual for the best instructions.
Basically, you drain the water lines and tanks by opening up the lower level lines and the drain on the hot water tank. Be sure to let them air drain by opening up the furthest sink faucets. There should also be a special drain for your ice line. Open it and let the ice maker cycle. Once gravity has emptied the majority of water, close off the drain ports and hook up your air hose. Turn on the air and open one faucet at a time and let the air flow out until it is dry, then move to the next. Don't forget your Washer if you have one. It may or may not need to be disconnected or cycled (see owner's manual for specifics). Also don't forget your outside shower if you have one.
Once everything is blown out, pour pink RV antifreeze into the drains. And you are done!
Colorado '15 Winnebago Forza 34T w/MKZ hybrid toad