I really don't mean this in an insulting way, but it sounds like you may be a little out of your league here.

I gave you the answer, but now you are asking how to implement it.

Do you have much experience with php or is it mostly copying/pasting?  If it is mostly copy/paste then I think it's going to be very hard to customize elgg to your needs.  I would suggest learning php first, or hiring a programmer.

Sounds like a neat feature to have for the profile manager. So what did you do to combine the simple date picker with the profile manager =)?

Nevermind i got it =)

I didn't figure out how to display it in age but i got it working the way i want it =). date/month/year