To add it go to User Control Panel >> Profile Tab >> and you'll find it down the bottom. Nothing real personal required, Favorite food (if you take food make sure its not pizza
Be aware that in the event that you do lose both your password and no longer have access to the email account I won't change it unless you have this filled in. Obviously this isn't going to apply to everyone as there are other ways I can determine it's actually you but in lot cases I won't be able to and out of privacy concerns will be forced to deny the request. You will have to register a new account in that case.
If you ever need to use this feature to reset your email and password contact me via email.
You could of course just make sure you don't lose the password or keep the email up to date. FYI the only thing a current email address is needed for is to reset a lost password. If you have access to the control panel you can change either at any time.