Left-click your mouse in the center of the moving applet to calibrate mouse control,
then move your mouse around the inside of the moving applet to move around the 3D world.
The moving applet initally loads at the upper-left hand corner of the height map.
Reload this page to reset the starting location to the upper-left hand corner of the height map.
Download the complete applet here, complete instructions (also contained in the ZIP) are here.