Once you’ve installed or updated the Lumia Selfie app, simply open the app and the app will automatically detect if a connected Treasure Tag is in range (using BT LE). A press of a button on the tag will then trigger the camera on your Lumia.
You can install Lumia Selfie app from here. Treasure Tag app has also been updated it seems and now one can set up quiet modes (defined by Wi-Fi networks).