You should be seeing yourself on the screen and hearing yourself on your headphones or speakers.
If you are not please close any other application (e.g.Skype) which may be using your camera, microphone or speakers.
Please also check that you have not disallowed e-therapy.uk access to your microphone and camera.
On Chrome there should be an camera icon on the right hand side of your address bar.
On Firefox there should be a firefox, camera and microphone at the top center of your main display.