There are multiple ways users can be added to events:
The user can self register to a session of an event t if there are spots available and the event is made accessible to the user via the user group expression under the tab "Visibility" for the events in the CMS.
The user can be assigned directly to the session by an admin or manager. This can be by opening the event in the CMS and assigning the user in the "Session assignment" tab. The user does not have to fall under the user group expression defined under the tab "Visibility" in order to be assigned.
The user can show interest in the event when all spots are taken (or spots is zero) and the event is made accessible to the user via the user group expression under the tab "Visibility" for the events in the CMS. The user's interest can be managed by opening the dropdown menu next to the user in the "Session assignment".
Once the session has past, you can confirm the user and his attendance to the session under the tab "Participants list" in the CMS.
If you wish to cancel the user and his attendance to the session, you can do so under the tab "Participants list" in the CMS.