Okay, so this doesn't exactly teach you how to audit as a Scientologist... but I think it is the closest to an explanation we are going to get. So, listen up & try to learn.
The following video serves as an introduction to the central practice of Scientology -- auditing.
Discovered, developed and codified by L. Ron Hubbard, the procedures of auditing represent a vast body of technology.
In Scientology churches around the world, Scientologists learn the skills of auditing and use them to achieve spiritual enlightenment and freedom.