When you went through the initial setup, you were asked to include a gmail account. Your phone automatically backs up all your contacts (Name, phone numbers, emails, birthdays, etc..) to your gmail account. If you remove backup assistant and delete all the contacts that you don't want, only the ones you leave will be backed up to google. If you want to do it the easiest way, sign into your google account from your computer's web browser and click the contacts link of the left side. Those are all the contacts on your phone, and when you make changes on there they will be pushed to your phone.