A new event is created by clicking on the day and time where you'd like to create the event. You can also drag the event to be as long as you like. From the calendar event window that opens you can click "More options", which opens a window from where you can edit more options for the event. You can also click the plus-icon on the bottom left corner that says "Create event" when hovering cursor over it. Clicking "Create event" opens the "More options" window immediately

Clicking save will create the event.