Answer:
each character has there own button combo that you have to press in the given amount of time the opponent is dizzy,
you can find out all of them by :
going to mortal kombat warehouse.com
select mk3
go down to whre you see choose your fight
each character has their own page of sprits, bios, and button combos are revealed on the move list along with a video showing it
that should help alot, hope this works
if you need more guides or walkthroughs, you could go to g4 or a forum. good luck
Mortal Kombat http://www.g4tv.com/games/xbox-360/63918/mortal-kombat/