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