In the calendar section of your GMail/Google Apps account there is a list on the left of calendars available to view.
At the bottom right of that list is the word “Add”
If you click this word and select “Add by URL” you can cut and paste the link. Ignore the checkbox about making it publicly available.
If you are using an Android phone this calendar will then sync to your Android phone, providing the account you add the calendar to is the account that you sync to your Android phone!