How to connect this motor driver board to Arduino to drive bidirectional motor?
I guess you have used DC Motor for your earlier cases? Or Step Motor with a logic on the stepper controllers?

Here you have two H Bridges which drives one Step Motor. So as I understand it, you have two PWM Inputs, one for each output channel to the coil windings of the stepper motor. Like an encoder signal you can set the direction with setting one pwm before the other. So the step motor is controlled via unipolar stepping.

For further help you need to say which motor you want to use with this card. But first I would look at the different stepping modes (unipolar and the two bipolar and maybe microstepping).

Greets