l know about the basic 'wedge' technique, that is spreading my skis at the back and narrowing them in the front. I'd like to the know the technique where you stop quickly by turning perpendicular to your forward motion.

pick up the down or up hill ski and turn and then plat it like the hockey

Once you can wedge turn you want to increase the pressure to your outside (of the turn) ski while releasing pressure of the inside ski then rapidly turn across the hill and pressure both uphill edges