1. Go to the event page.
  2. Tap the Manage people button. There are three tabs on this page,
    • Attendees
    • Organizers
    • Viewers
  3. Tap the PlusĀ [+] button.
  4. Select Add attendee, Add organizer or Add viewer.
  5. Search and select the users or group you want to add.
  6. Tap Done.