1. Login to your SharePoint website and locate the name of the calendar you would like to add to Outlook. In my case, it's called "Team Calendar". Click on the name to pull up that calendar.
2. Now on the SharePoint toolbar, there is a section called "Calendar Tools" with a tab called "Calendar". Click on that tab.
3. Next click on the button that says "Connect to Outlook". You'll probably see one or two prompts popup that will ask that you want to confirm this action.
4. After you've confirmed the prompts, you'll now see your calendar has been added to Outlook. You can use the checkboxes to turn on and off various calendars, depending on how many you want to see at a time. You can fully interact with this SharePoint calendar - add/edit/delete appointments, drag and drop between your other personal calendars, etc.