To use a black polishing compound, the first thing to do is read its instruction manual well to know if there are any compulsory precautions to take. To start, let out the compound on a hand applicator or a polisher, or a buffer. Now rub the wax on the surface where you want to use it.  Using hand might need you to indulge extra strength & effort. And if you use a machine, rotate it in a circular motion until you get the desired results.