Hey, welcome 4mrsdivine :)
What are you asking how to do?
If you find your son's Ship and Div. on here it's a discussion. You won't be able to add it necessarily but there is a link at the top or bottom of the page that says "Follow" and it will send you an email whenever a new post is made.
If your son's Ship and Div. isn't on here and he graduated this past July at the centennial PIR then you can add a new discussion to help you find other moms and girlfriends with Sailors who were in the same Div. :).
I hope this helps :) if you need any clarification on anything or need answers to any other questions there will always be someone on here to help you out :).