For specific events, you as a buyer should provide Ticket details to your seller, such as Name, Date of Birth, Email, Nationality etc., in order for him to be able to update the needed within the system and include correct details for you and your guests.
You can provide these details at checkout or after you made the order in a reasonable time before the event (You will be informed when is time to update the ticket holder details).
You can update the Ticket holder details by going to My Purchases => +Add Personal info on ticket holder(s)
After you click the β+β you will be able to put all the details of your Guest(s).
Your seller has an option to Approve the Information provided, and as soon as it is approved, you are no longer able to update the details, hence be precise when updating the Ticket holder details!