Here's one from ebay. Left hand lever, you can see where the handlebar would sit with the clamp - it would be top to bottom of the picture, to the left of the shifter, with the bar end at the top of the picture.
To pull the brake, you pull the lever towards the bar as normal (pulling towards the left of the photo).
To change gear, you move the same lever up or down relative to the handlebars (put your fingers under it and flick it up, or fingers on top of it and flick it down). I.e. to change the gears the lever moves up towards the XTR logo, or down away from it, staying the same distance away from the bars. Hope that makes sense.
Once you get used to them, you can brake and change gear at the same time by combining both motions.
These levers were combined with a low normal rear mech - i.e. when the cable is released it moves to the biggest sprocket rather than the smallest as per conventional ones. It means that the same action on each side has the same effect - pushing down on either side puts you in a higher gear.