Adding power steering fluid on 2004 Chevrolet Impala

I know the power steering resevoir is under the alternator, but how do I add power steering fluid?

Asked by for the 2004 Chevrolet Impala
The power steering reservoir is mounted/part of the power steering pump, at the top is a cap that screws off, a funnel is needed (available in any hardware store) to avoid spilling the fluid on the fan belt. The GM part # of the fluid is 89021184.