On an iPhone: Click this link to add to your phone calendar https://www.google.com/calendar/ical/orientation.mrgc%40gmail.com/public/basic.ics
On Android: Read this Tutorial The url is below.
On a Computer -
If you use Google Calendar with a Gmail account.
Click the + button at the bottom right inside the calendar.
If you use iCal programs or services.
Left side of Calendar page, click the right drop down and click "Add by URL" and enter the following address. https://www.google.com/calendar/ical/orientation.mrgc%40gmail.com/public/basic.ics
This will work with other programs that use ical.
This link is a separate page if you would like to bookmark it