First, enable the "Debug mode" code. During game play, press the button configured as "B" on the Genesis and Sonic should become an object somewhere on the level. Press the button configured as "C" to"paste" that object in the level. To resume game play, the button configured as "B". To change the object, press the button configured as "A" on the Genesis while editing the level. You can also move the object in the air, etc. to truly make your own areas. You can also move across obstacles and turn back to Sonic to cut points in the level.