there is a snap ring sorta thing that hugs the outside of the sprocket on the hub. usually takes me 2 flathead screwdrivers to get the thing off, you should see the gap in the retainer ring, pry it open until the ring is large enough that you can pop it off the hub.
the other thing is the spocket on the hub will probly have 3 little "teeth" on the inside that fit on the hub and kind of lock it in positioon so it spins with the hub, doesnt look like the skiptooth has them on the inside of it, may have to figure that one out when the time comes ?