Popups, as well as all other Units, don't come with Specific Manufacture Instructions on how to winterize. It is all a generalization, and basic process.
Here is a clear and precise Youtube tutorial on how to winterize using the Anti-freeze method. There is also a Compression Method of blowing out your lines. But, this is my how-to method.
There are other tutorials on Youtube. Just type in PopUp Winterizing. Hope this helps.