The C and Z buttons have the following functions: Dodge, useful for dodging attacks, you can use side dodge without moving, or roll, if you are hit in the air, you can fall rolling, and the other button is the Counter function - attack, when you are on defense and receive an enemy attack, press the button to push the opponent away (consumes Rage Art bar)
Block in almost all fighting games, excluding mortal kombat and soul calibur, uses 4 or back to block, this is practially standard for the 2d fighting game genre, its clunky to get used to if you're transitioning from games LIKE mortal kombat or soul calibur but i hope you eventually get to this style of controls considering this is pretty much the same no matter where you go :)
