The Internet calendar must be shared publicly and the URL should end with. After you've entered the name, select Add to search for and add the calendar. This box works just like the To box on a new email message.
To add a calendar that belongs to someone in your organization (or a resource calendar), click 'Add from directory' on the left hand side, and enter their name (or email address) in Enter a name or email address box.Click Add Calendar on the left hand side.
