The easiest way to access your calendar and its settings is by clicking the "Calendar" button at the bottom-left corner of Outlook 2013.
Sharing Your Calendar
1) In the top pane, select "Calendar Permissions".
2) In the window that appears you are able to select users and adjust their permission levels. If the person's name that you are trying to share a calendar with is not listed then click "Add..." to search for them and add them to the list.
3) Once you have highlighted the person you wish to share your calendar with, choose the apropriate permission level for them and then click "OK".
Opening A Shared Calendar
1) On the top pane, click "Open Calendar" and select "From Address Book..." in the drop-down menu that appears.
2) In the window that pops up, you are able to select an address book to search from and also search for users within that address book. Once you have selected a user or group of users, click on "OK". If the person needs to grant you access, they will need to do so before you're able to see their calendar.