To cast programmes to your TV from your mobile app, you must first download the app and pair it with your Netgem TV box. Find directions on how to pair your mobile app here.
This shows a mobile app that is not connected to a Netgem TV:
Tap the Chromecast option to connect your Box.
This shows a mobile app that is connected to a Netgem Box:
You can now use your mobile app to cast programmes to your Netgem Box.