Oh. . .
I didn't think I'd have to explain this so early. . .
OK, see the top of the page, it saids Home, Calendar, Gallery, FAQ, etc?
Click on Calendar.
OK, if you fast forward to your birthday, and you want people to know it's your birthday then, you click on the day of your birthday.
Add an Event and say "My birthday".
The Event will appear in this topic.
Try it.
Go to your birthday and add the event.