Hi Bill,
welcome to the site - this is also a useful diagram - note that you need a relay, otherwise you will need to pull the 12S plug out each time you stop your car engine, as the fridge will still be drawing off your car battery!
Gram
------------- What's the difference between a chicken?
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets