Your son does not need to do anything on his end. InmateAid is a service built entirely for the people on the outside, and inmates do not have internet access to register for anything even if they wanted to.
You create the account, set up your son's inmate profile, and handle everything from your side. Once his profile is in the system, you can send letters, photos, postcards, and access any of the other services InmateAid offers. Everything gets processed and sent from InmateAid's facility and arrives at the prison through the standard mail channel your son already uses.
InmateAid has been around since April 2012, and the service is well known inside correctional facilities. Inmates recognize the logo on the envelope and know exactly what it means when something arrives from InmateAid. Getting mail through the service is a welcome thing for anyone inside.
If you want to try the service before committing, reach out to InmateAid directly by email and ask about available discount coupons. It is a straightforward way to get started and see how the service works before your first full order.