UBB.threads PHP Forum Software Community Forums UBB.threads Version 7/8 Support Private calendar box

I am in the process of upgrading to 7.4.1 and have enabled the "Private Calendar" option to be displayed. This is all new and I am ashamed to ask, "How does this Private Calendar" work? All I see is the box, "My Calendar" with the note, "You have no private calendar entries".

A little gentle instruction would be greatly appreciated.