You said you applied 5V to the input. You must realize you must apply voltages to BOTH the INA and INB nodes. When INA is 5V, INB must be 0V. When INB is 5V, INA must be 0V. Complementary voltages must be applied to the inputs to get complementary voltages at the outputs. This is how an H-bridge works. It allows the differential output voltage to swing from +12V to -12V so the motor can go from forward to reverse. You will need to have a circuit to convert your single ended input voltage signal to a differential voltage signal to drive the input of the H-bridge.