Hover over ?Instructions? at the bottom right.
Use the controls to the right to alter the generation algorithm. Press that red ?PushDaButtn? to start the generation process.
?B? key cycles background color from black to white.
?P? key pauses and unpauses the generation process. You can conveniently change the controls while paused and they will take effect immediately after you unpause.
Conveniently use the ?Scale? control to make the whole generation smaller (like zooming out) or larger (like zooming in).