The way this applet works is that you modify the sliding bars on the side to whatever you want and this affects the picture that is displayed. This list below is what you can change
Fixed Circle’s Radius
Moving Circle’s Radius
Moving Circle Offset
Red
Green
Blue
Revolutions in Radian
The circle settings control what it looks like and the color settings control what color your spirograph is. Its pretty awesome!!
http://www.wordsmith.org/anu/java/spirograph.html