Use tape to cover any surface not to be blasted. This is the easiest way to make sure the area not to be cleaned is not accidentally blasted.
Add baking soda to cylinder of the soda blaster and hook the air line to the air compressor.
Put on safety goggles and dust mask. Turn on the air compressor. If a test area is available, use it to become acquainted with using the blaster. Control the flow of the blaster by reducing pressure, backing the hose off a bit or aiming at different angles.
Strip and clean the surface desired and wash away the powdered residue with water or wait for the next rain.