Push "Pause/Cancel" twice on the Whirlpool Duet's control panel, and press "Power."
Push "Drain/Spin" and hold "Start" for one second to have the water drain from the washer.
Wait for all of the water to drain out the machine and remove the clothing from the washer. Turn the washer's knob to the desired wash cycle and temperature.
Pull open the dispenser drawer on the front of the Duet washer and pour the liquid detergent into the compartment labeled "Main wash" until it fills the compartment's line.
Close the dispenser drawer and push "Start" to begin the new wash cycle.