Paste the code to you Shopify store’s HTML field.
Next, go to your Shopify 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 Shopify’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 Form Builder app on your Shopify store.