Share a Calendar - Delegate Access

From the Calendar - start at the 

Home tab

Select “Share Calendar” > “Calendar” from the drop down menu.

Calendar Properties Panel

Select “Add” and add the user you wish to give permission

With the user selected, choose the permission level.  Hovering over the permission will display what rights are granted.

Edit – the user can manipulate and delete existing appointments

Delegate – in addition can create appointments

Note: Calendar items marked Private are protected. Most people you share your calendar with see only the time of items marked Private, not the subject, location, or other details. The exception to this is if you select the Let delegate view private events check box.