Right-click Calendar from Folders - your user name and select Properties.
The Calendar Properties window appears.
Select the Permissions tab.
Click Add user.
In the Add User dialog, enter the userID and choose the permission settings, or click Search to search for a user.
Click OK to delegate access to your calendar to the specified user.
If you are granted access to another calendar, and create an event in that calendar, the calendar owner is listed as the organizer of that event. Any email reminders sent about that event is sent on behalf of the calendar owner.