To show your class openings and number of wait list spaces taken up in each class, go to Configure | Preferences, scroll to the Preference section, click edit, check the box next to Show Class openings, and save.
With Show Class Openings enabled in preferences, the number of open spaces for all classes will be visible on the public portal. This setting is global and can only be configured on or off for all offerings. If a class has filled and a waitlist has started, the openings will show negative numbers to show how many are on the waitlist (i.e. -3 means there are three people on the waitlist). If the class is not full, the number of available spaces will be visible.
Whether this is enabled or not, waitlisted customers can login to their accounts on your public online registration site, view their waitlisted enrollment, and see what number they are on the waitlist.