This will be your first achievement of the game. Win your first battle against real enemies.
Before fighting for real, I recommend you go to the arena and do the battle tutorial there. The last tutorial's instructions are vague, what they mean is to perform a smackdown do a hero action and attack an enemy. When it is airborne jump (X) and attack it. If you knock it to the ground, that is a smackdown.
Ok, that taken care of, move the cursor around any of the two tiles adjacent to the arena. The fights shouldn't be too much of a bother if you did the tutorial.