After installing compatible wrapper, a new option will be available in Gecko Theme under WP Admin -> Gecko -> Settings -> App tab.
Currently there is only one option available there, to enable or disable Dedicated app widget positions. What this option will do is simply enable the new widget positions in the Gecko theme app context. It is not necessary to use it unless you want to specifically show some widgets in that positions on mobile phones only. New positions will be available for you to choose when publishing the widget and they’ll have the suffix (Mobile App).