Step 1: Jack up front of car, place on jackstands for safety. Make sure car is in neutral and start engine, roll down window.
Step 2: Take a fluid pump (manual or vacuum) and remove 3/4 of the fluid in the resovoir.
Step 3: Fill resovoir back up. Now grab steering wheel and turn wheels back and forth, barely touching the stops, at a medium-slow speed. This is going to move the fluid through the system.
Step 4: Repeat steps 2 and 3 until the fluid in the resovoir matches the new fluid coming out of the bottle. I used less than 3 quarts of fluid on mine.
Step 5: When there is no more bubbles coming up when the wheel is turned back and forth, youre done. Top off to full mark and put the car back on the ground. Congratulations, you now have nice, clean fluid in your power steering system.
Note: Power Steering stop leak should be a last resort, that stuff is nasty and gums up your whole system. I bought a power steering pump gasket kit from Nissan and replaced a few leaking seals when I did mine.