You can easily turn holidays on and off in your calendar. Just:

• Click on the gray 'Calendar' tab
• Click on 'Customize' on the blue bar

You will then see:

Choose the holidays you want to include, and click on the blue Update button. (if the holidays do not show up you might try logging out of your account and logging back in again).

(U.S. holidays, US holidays; U.K. holidays UK holidays, Canada, Canadian holidays, Mexican holidays, Protestant holidays, Catholic holidays, Jewish holidays, moon phases, moon calendar, lunar calendar, lunar phases, full moon, show holidays, holiday overlays, turn holidays on, turn holidays off)