A series can be:
- weekly
- fortnightly, every two weeks
- monthly, for example the second and last Sunday
You add it once, with “Create event”. Repeating dates build themselves. The event has its own public page. If the same event already exists at that venue and time, you are told.
That is what is automatic for the organiser: repeating dates, the public page and the duplicate warning. There is no automatic synchronisation of the agenda with other sources. In Buenos Aires and London the agenda is checked against local sources.
Adding the event is covered in Create your first event.