Theft deterrent

I have a 2002 Lincoln LS that my girlfriend misplaced the key to. Then 1 of her bright friends decided to try and put his Lincoln key in mine and see if he couldn't get it started. So as I'm at work all week dummy 1 (girlfriend) and dummy 2 (friend) try and makes friends spare start the lincoln. I come home find the keys and go to start the car and the anti-theft is blinking rapidly. What is the sequence of steps to reset the theft deteriont system with the original keys.