These two sets of pads are connected internally so you can use breadboard or terminal blocks to provide motor power. Use 6.5V-45VDC to power the motor and the chip. This isn't the same as the logic level of the chip, which is up to 5.5 VDC. You do not have to provide a logic level power supply to the chip, how nice is that?
These are the inputs to the motor control. IN2 goes to OUT2, IN1 goes to IN1. Use up to 5.5V DC logic on these pins. You can PWM the inputs up to 200KHz, but lower frequencies will be more efficient.
Pretty simple - this is where your motor goes! Works with any DC brushed motor. Use thick wires to avoid dropping voltage across the wire resistance