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

This will add a brand new empty Row layer with a single Column layer inside of it, which you can then start populating with content layers and customizing the styles (eg. adding a background, adjusting padding and spacing, etc) in Figma as needed.