To get your facebook.com id, login into your facebook account and move to message section. You will get an automation message follow that process and get your @facebook.com account. Also update your phone number to your account, when someone sends a message to you in facebook you will be notified by a sms. To conform your facebook id, go to your profile (or) page, in that move to Contact Information (Available at last column) in that you can find you own e-mail id and facebook id.
Note: This service is not available for every one.
If you cant find facebook id section in message , then you have to request for one. Go to the following address and request for a invitation
http://www.facebook.com/about/messages/ hope this helped you…!!!