From your event page, click "Edit"
2. Go to the Seat Limit section.
Click "YES", and set the type in the number of seats you'd like to offer.
Then, decide whether you would like to allow people who have received the code to confirm their attendance beyond the seat limit set (e.g. an event's registration limit has been met, but someone attends an event without registering. Should they be allowed to confirm their attendance?).
Finally, decide whether you would like to allow users to join a waitlist if the registration limit is hit. Users will be added to the waitlist in the order that they entered it if anyone un-registers from the event. See this article for more details about the waitlist: Using Event Waitlists
3. When people are browsing events, they will know how many seats are remaining.
4. If an event's seat limit has been reached and the waitlist has been enabled, the user will see this: