Normally, after replacing a component on the power steering system, air will be introduced to the system. The standard procedure has always been to start the engine, and turn the steering wheel all the way to the left, then all the way to the right. Repeat a few times, then check the fluid level and top off as needed. Hope this helps.
Good advice......also if you feel like being nice to your car you can jack up the front end just enough to get the weight off the wheels and turn it without much resistance, this is good when you replace a pump or such and lose a large amount of fluid.