Looking to get my armed guard license in NYC.?

I am an unarmed guard in NYC looking to move up. However I don't know what the first step is. Do I go to school first and then optain my gun permit. I think it would make more sense to get the permit first since you need to have your own gun for class. This leads me to my next question, I am told that in NYC you need a letter of nessessity in order to obtain a fire arm. How does one go about getting this. Also people say that only those who are ex cops or ex correction officers can apply to be armed guards. As you can clearly see I need direction so please help tell me what to do first, second, third etc.