Position 1 is sitting on the bike, butt in the seat, hands holding the bottom of the handlebars.
Position 2 is butt off seat, standing straight up, hands near the bottom of the handlebars (at the curved part).
Position 3 is butt off the seat and in the air, upper body bent forward, hands at the top of the handlebars.
I tried to find a video or even pictures of these, but couldn't find anything.
Spinning must not have the online community that xfit has.
Jumps would be moving from p1 to p2 on counts of 4 (4 up, 4 down), or going from p1 to p3 on counts of 8. Obviously you can do them on any count, with a ton of resistance, or in a sprint, etc, etc.