Hi Saffron

While in debug mode, open Sales > Product view, go to the tab "Sales", and you must have the Ribbon option.

After picking a ribbon and saving, click the action button "Go on Website" to see your changes.

You can also add the ribbon on the Website, through the Product listing, open the "Edit", select a product, go to the tab Customize, and on the bottom, you should have the grid showing the ribbon position, and a list of possible ribbons you can use.