http://jva.ontariostrongman.ca/RL.htm
The picture is not a good example IMO because the lifters back is flat, not arched, and I don't advise doing them off a platform.
Basicly, like a GM with the bar in your hands. Unrack the bar, walk a step back, make sure your feet are even and your back is tight, push your butt backwards while maintaining the lower back arch, and lower the bar bar continuing to push the butt back until your hams feel a good stretch, then contract your ass/hams/hips and push them forward.
The Key differences:
The back is arched, not flat or rounded
The movement should be almost all butt back/butt foward (at least in how it "looks") and less of a "pull"
The movement is started from lockout, not off the floor
I've also found the "snatch grip" variation of this lift to be fun too, as it hits the upper back harder and increases the ROM of the pull somewhat.
I advise taking some time to work with light weights to get the form down if you've never done it before