Most brake systems have a sensor that will start to make a squealing or squeaking sound when the brakes are wearing down. This squealing is usually heard when the vehicle is in motion but will stop when the brake is pressed. Always get the vehicle into be serviced when you hear this sound.
Some new brakes or harder pads on brakes will make a grinding noise when the brake is applied. If you hear a grinding sound have it checked by your mechanic and do not continue to drive the vehicle as you may not have full braking power.
Changing your own brake pads or shoes is not that difficult, but you should have the proper tools and have a general idea of how to proceed. Most vehicle manuals provide the basic information plus there are also basic mechanic classes that can provide this information.
