Please Brief me on Prep school

So just this morning I was given an offer to attend NAPS. I haven't accepted yet because I am still waiting on my USMA decision. I am delighted with this opportunity but I honestly have no idea how Prep schools work. All I know is that candidates who are lacking academically get sent here to prepare for the next class.

But upon graduation from the Preparatory schools does the candidates automatically get appointed to their respective Academies? Please input any information regarding the...

Please Brief me on Prep school