If you need to change your name for whatever reason (i.e. after getting married), you need to come by the Registrar's office to show official documentation of a legal name change. For most cases, just your marriage license will do.
Unfortunately, at this time, this process cannot be done online.
After you have officially changed your name with the Registrar's Office, stop by Support Central to have a new ID card printed. If you have an OC issued laptop and would like to change your username, please bring your laptop with you when you get your new ID card printed.