You can find Events that you haven't added to your Calendar from Groups that you are a member of and from individuals that have given you access to private Events.
To do this simply:
1. Open up you Calendar and click on the 'Find Events' icon.
2. Scroll through available Events or Search Events you are looking for then click on the Event name to open the Event page
3. Click on 'Add to My Calendar'
NOTE: If this is a Repeat Event you will be asked if you want to add all the Events, some of the Events or just this Event to your Calendar.