How to Share a Calendar
Right click on the calendar you want to share.
Select "Sharing..." on the drop down menu.
To share with an individual click the add button.
Enter your contact's name or email address in the search bar.
Select the name from the drop down list then click the "Add" button in the bottom right-hand corner of the window.
Your contact will now appear in the previous window.
Tick the "Subscribe User" box and the calendar will appear in their list of calendars.
Double Click the name to bring up the permissions window.
The drop down menus in red need to be changed from the default settings otherwise your contact has no access to the calendar.
The red boxes let you set different classes of people to different access levels, and blue lets you give editing power to the contact.