(I can only comment on how the USNA system works)
The Candidate Information System (CIS) is the online user-interface for the application and admission process.
If he has already done a preliminary application, then most likely he has a candidate number.
He uses this number (along with his first and last name and the last 4 digits of his SSN) to login to the CIS.
Logging on to the CIS (from the
USNA Admissions page, click on "
Continue") will update him on what he needs to finish, in order to have his application complete.
After logging in, "Application Status" is the first thing on the list.