The quickest way to add a new Hero is either to add a preset starter component (mostly from the "CTA" tab) or to use the Quick Add Element dropdown at the bottom of the plugin to insert a new blank Hero layer to your email design, when your Emailify email Figma frame is selected.

This will add a brand new empty Hero layer with a placeholder background image fill set on it.

You can then start populating it with content layers and customizing the styles (eg. adding a background, adjusting padding and spacing, etc) in Figma as needed.