OK, this would have been cooler if it was done a long time ago when most people registered, but better late than never. When you register, or update your listing, there is a place to enter you birthday. Just the month and day (no, not the year. Most of us are trying to forget that at this point).
This is really just for fun. Anyone who has a birthday on any given day will be listed on the main Alumni Directory page. So if someone you know is having a birthday you could send them a birthday greeting. Or maybe someone you haven’t heard from in a while will send you one. But other than people I know pretty closely and anyone who registers from this week on, no one else has a birthday saved right now.
So if you have a password, go ahead and login and add your birthday. If you don’t have a password, try the FAQ page.
Once your birthday is on record, you won’t see the option to set it again which shouldn’t be a problem. If you were born on Feb. 29, all bets are off.