How do i flush my power steering in my 2003 mercury mountaineer

You need to raise the vehicle so that the front tires are off the ground and place on jackstands. Make sure the power steering reservoir is full. With the engine off (not running) turn the steering wheel from stop to stop 2 or 3 times. Recheck the fluid level and add if necessary. Lower the vehicle to the ground. Start the engine and slowly turn from stop to stop 2 or 3 times. Recheck fluid level. If no groaning noise is heard when the engine is running or the steering wheel is turned, and no foam is observed in the reservoir when engine is stopped, then bleeding is complete.