Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
It sounds like the power steering fluid is low, if the sound is there when your not moving. You might want to check the level of it and make sure it's full. Then turn the wheel with the engine running a few times, (to get the air out) and see how it does.
If the fluid appears to be very low, you will want to have the system checked for leaks. Thanks