You'll want a small compressor soon enough. The process is near to this. You must first select the airbrush that you're going to do. Try to get the best you can here. Remember that this is the instrument that can make or break your paint job.
Airbrushes come in three flavors.
Paint is controlled by a separate adjustment. Double Action, again, regulates air by pushing the trigger. The more it's leaned on, the more air is let through. Now you pull back on the trigger to release fluids. More pull back, more paint.