Navigate to the Holidays page by;
Hovering over the navigation menu to the left
Left-click on Operating Hours
Left-click on Holidays in the dropdown menu
Once you have completed the steps above, you will see a similar page to the one below:
Begin by selecting a Source number at the top left of the screen.
Next, select the date in which you wish to set the holiday to.
Then type in the name of the holiday. You can also decide if you wish to make it a recurring holiday. Once you are ready, click Save.