Welcome to help. Most of the parameters are described at Mozilla's Web audio API documentation . The rest is explained here.
Press shift-key to play sound at the cursor. Listener is positioned at the ear.
To test different effects, disable panner, so that distance to the listener does not affect effects. You may also keep shift down while tempering with the controls to hear immediate effect.
If something gets jammed, reload the page. If you hear mixed white noise and waveform, try changing oscillator waveform.
To avoid sound clipping and ear damage, keep dynamics compressor always on.
In convolver node, you can adjust impulse response used to calculate convolution with the sound signal.