To play QB Battle, you select one game mode (for simplicity's sake, "Versus Battle", a 1 on 1 game against another player), and both of you select your characters.
Then, both of you see the opponent's character in your side of the screen (you're supposed to see your opponent at all times; when playing in real life, you and your opponent swap your books for that purpose), and then each of you select a maneuver (by bringing up the maneuver list).
Those maneuvers have a number attached to them, that represents the even page number both you and the other player must consider to determine the outcome of the attack (when playing in real life, you search for the matrix in the even pages; in QB Battle, it's all automatic), and then each of you arrive to a new odd page that shows the outcome of those attacks.
If your opponent's character arrives at a score page, you damage your opponent if the sum if the score damage plus your selected maneuver's damage is greater than zero. The attack's outcomes also come with a set of restrictions both of you must take into account when selecting the next move (plus an extra set of restrictions if you do critical damage), and the battle continues like this until either your Body Points or your opponent's are equal or lower than 0.
It may look a little complicated at first (and I guess it is, if you play with the actual books), but since the app automatizes most of it, you'll probably get the hang of it real quick.
