Besides having an authorized person perform the ceremony, you need to have 2 witnesses at the ceremony. The witnesses need to be at least 16 years old. They sign your marriage certificate to prove they were there.
If your ceremony is being performed by a religious official, the ceremony must follow the traditions of your religion.
If the ceremony is being performed by a judge, court administrator, or other non-religious individual, you must declare that you take the other person as your husband, wife, or spouse at some point in the ceremony.