Firstly, install the APK on your phone. Next, download the marker image from the repo as well. To have the graph appear on your screens, you'll need to have the marker image either printed out or displayed on a different device. Hold the marker in front of your camera after you've entered the .csv file into gARphics.
This current version only supports marker-based tracking in augmented reality. A future version would support markerless tracking (using an arbitrary user-defined marker to display graph).