If you do a search on "Winterizing" you will find infornmation faster than waiting for an answer here.
There is a search tutorial in the "Forum Tech Support" forum, which will help you maximize you search.
It sounds like your hot water heater wasnt by-passed, also you will want to add the antifreeze at the pump, not the fresh water tank. If you dont have a hot water by-pass valve, you will want to add one.
You can purchase a Winterizing Kit which will allow you to add the antifreeze at the pump.
As for the hot water heater, most are accessed from a panel on the exterior. There should be a large plug that needs removed to drain the heater, but make sure you open the pressure relief valve first, or you will get soaked.