Paste the code to you BigCommerce store’s HTML field.
Next, go to your BigCommerce store and find the HTML field. It is most likely in the form of an HTML/Code widget or module which you can find on BigCommerce’s dashboard. Add it to your page, and paste the code you’ve copied before to the HTML field. Save and update, and that’s it, you should have Common Ninja’s Countdown app on your BigCommerce store.