Who can create an Event?

Only "Group administrator"  or "Group publisher" can create events.

How to create an Event?

You could create an event via "Create content | event" in the User panel menu visible to the right side of the top banner when you're logged in - or by clicking on

http://ec.europa.eu/eurostat/cros/node/add/cros-event

Where are the events displayed?

Upcoming events are displayed in chronological order, grouped by month,  under upcoming events (accessible by clicking on "Events" on the drop-down menu anywhere in the CROS portal.