The hot water heater should have been drained before winterizing. If it wasn't cleaned or if the sacrificial was not inspected you should do it at this time. Open the door that you use to light your water heater.
Find the large brass plug at the end of the sacrificial anode. It is located at the bottom of your hot water heater.
Using a 1/2" drive, a 6" extension and a socket (I needed an 1 1/16"), remove the large brass plug of the sacrificial anode.
Inspect the sacrificial anode and replace if needed. Add teflon to the thread and replace the anode.