i tried spining the right stick like in the first game, but it doesnt seem to work.  does it have something to do with the camera zooming in?

I have the same problem, unfortunately i think we will have to wait for the tutorial in the main game.

To do a submission you have to push the right stick in not just spin it. Spinning the stick makes a transission  (moveing around on the opponent)

and its best if you are in a dominant position to get it to complete.....