Welcome melrose73 to irv2.
Your hot water tank will have a plastic or metal nut with anode rod attached.
It will be on the bottom face of WH and you would remove to drain. Open the relief valve lever to get air into tank for quicker water flow.
Here is a link to both type water heaters.
Your WH may also have
BYPASS VALVES to operate so you will not fill with antifreeze when winterizing.