Power Steering Gearbox? on 2006 Mercedes-Benz CLK350

I believe that my power steering "gearbox" is low on fluid. Can you please tell me where exactly the gearbox and what type of fluid can be used?

Asked by for the 2006 Mercedes-Benz CLK350
Most owner's manuals have a maintenance section that describes basic fluid checks and what types of fluids are acceptable. Do you have any leaks on your car? Are you hearing some kind of whining noise?