Open your Outlook Web App.
Click on “Calendar” on the toolbar at the top-right of your screen.
Right-click on “Calendar”, found under “My calendars” on the left-side bar. Please note that the box next to “Calendar” needs to be checked.
Click on “Share calendar”
Type the name of the person you want to share your calendar with.
Once the person is found in the address book, you can set the permission level you want to grant him/her from the drop-down menu