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) Click on "Share Calendar" on the top pane.
2) From the window that pops up you can select people to share your calendar with as well as what they can see on your calendar. From this screen you can also request permission to view the calendars of the people you send yours to.
Once you've finished choosing from these options and including people, click the "Send" button the left-hand side.
Opening Another Person's/Group's 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.
Adjusting Calendar Permissions
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. Once you have selected the permission level that you wish to set for a particular user, click the "OK" button.