HowTo change the kinds of Events
Plone has a default set of Events you can publish. You can customize the names of the events in the ZMI.
Plone has a set of Event types you can create. The names of the event types are stored in the plone site and can be customized. I added Class, Seminar and Workshop to the list of events.
Enter the ZMI, go to /portal_metadata, and select the Elements tab. Make sure the "Subject" element is selected. There is a Vocabulary defined for the Event type. You can alter the Vocabulary here.