New to AppStudio, but how the heck do you add a GroupBox?

Dragging a GroupBox or 1Column Object onto “Orders” Screen in AppStudio is Gray unless you drop it into another box. How do you add more to the canvas?
Want another Grou Box below the CounterSale and Lined Group in the white area…

Got it!
I had to select the next level down in the Application Map and then could add the GroupBox and Container Objects.
George Hicks