Why don't the brake lights come on?

Were does a brake switch goes in a 2004 Cadillac CTS 3.6

In an article I found that fixed my 2004 Cadillac CTS with no brake lights. Cadillac will not tell you, but this is a common problem that is part of a service bulletin that requires reprogramming of the Body Control Module due to computer ground fault of the brake lights. It's about one hour of labor with the cost of both brake light bulb replacement (that's $100 + tax). Find the article in Google Plus - CTS Cadillac Brake Light Not Working - 3rd Brake Light OK."

To web talker you said you have to reprogram the body control modular how do you do that