Last I knew (and this was a while ago), you start out around $50-$60 an hour, and you pay 24HourFitness 15%.
The more certifications you have, the higher you are allowed to charge your clients. And also the more attractive you are to clients because they feel the more education you have, the more you will be able to do for them.
It will take time before you are working 40 hour weeks… you will probably need about 40 clients to achieve that.