From your confirmation email, you can either click the Order Number or Manage Attendees to edit information for your attendees.
When the attendees for your order are listed, click on the attendee that you want to update and then select the desired action as seen in the screenshot below. Not only can you edit/complete info, but you can also view the ticket, print your ticket, donate back your ticket, change the ticket type, send the ticket as a gift, share it, join a group, or make a payment if applicable.
Any additional financial costs will require payment in order to process the change. Any changes that would result in a refund will attempt to go back to the original card if possible. If not possible, you will be prompted for credit card information.
Additionally, if you want to see or edit information specific to the order placed and not each individual attendee, you can click in the top right corner, Order Details, also shown in the screenshot above.
If you cannot locate your confirmation email, learn how to find your order here and follow the instructions to get here.