As you haven't yet finished your sixth form studies, the NAIA requires a letter to be sent from your school. This must be dated March 1st or later.
Once this has been produced, the person who has written and signed the letter needs to email it as an attachment to
InCred@naia.org with your InCred application ID # and name as the subject. They need to ensure they send it from a school email address and have a school signature when sending.