To have a feeling of g4view on your device you can have your first run by shooting positrons in a simple electromagnetic calorimeter. Use "examples/calorimeter" to create a Geant4 geometry for this piece of detector and visualize it :
This simple detector is composed of ten plates of lead (10 millimeters width each) separated by liquid argon chambers (5 mm each).
Then return to the main menu by touching (clicking) the bottom "meta zone" and choose the "Start run" button. Click the "Ok" button in the panel that proposes to "start a run" (Geant4 terminology). After a few seconds so that Geant4 initializes the simulation, you should see "events flashing" and the below histogram being filled. At the "end of run", after having shoot an hundred of events you should see something as :
Particles in blue are photons and the ones in yellow are electrons or positrons. The "primary particles" are positrons with an energy of 1 GeV. The plot shows the energy deposited in the plates and in the in-between liquid argon chambers. Here the maximum of energy is absorbed in the third plate