hotzenplotz,
It is just like Farmer1 said. Have a look at a car's disc brake as they are pretty similar. It's just that you have two 'independant systems' in a helicopter
In most aircraft, to apply the brakes you simply push the top of the tailrotor pedals.
This means that you can use the brakes at the same time as applying tailrotor yaw control. The action of doing these at the same time can mean you can almost turn on the spot.
cl12pv2s