To buy a car in an auto auction, start by researching available listings, such as the Chevrolet Equinox LT 2015 with VIN 2gnalbek0f6103539. You can find this specific listing at https://carfast-express.com/auction/lots/69585932-chevrolet-equinox-lt-2015-vin-2gnalbek0f6103539. Inspect the car's condition, set a budget, and register for the auction. On the auction day, place your bids carefully, keeping track of the competition, and finalize the purchase if you win.