Everything you ever wanted to know about the CFA is on the USNA website HERE.
Your DS only has to input his coach's name and EMail address into the Candidate Information Portal field, and then the coach will get an EMail with instructions as to how to enter the data from the Assessment.
If he intends to retake, he needs to get his current scores erased so new ones can be entered. To do that, he needs to contact his RD and ask to have it done.
