I believe the 2006 is the E90 vehicle.
If you mean by brake light the brake pad warning light these are the steps to access the services for resetting.First the brakes would have to be replaced along with the sensor.
1. turn the ignition all the way on without starting the car
2. wait until the time and outside temp is displayed in the check control.
Make sure the door is shut and buckle the sealt belt.
3. press and hold the trip odometer reset(left button)
until the service menu is displayed
4. using the scroll knob on the turn signal stalk, select the service item to be reset
5. press the "BC" button on the end of the turn signal stock 1 time to select the item
6. you will see "RESET?" under the maintenance item
7. press and hold the "BC" button to reset the counter
Edited by BmwMasterTech on 10/25/2009 at 1:56 PM EST