This adds another node to the Node Editor. Each node contains one or more adjustments,
and by combining several nodes worth of adjustments, you can build extremely sophisticated
grades. In this case, you’re going to create a “secondary” correction, which is an adjustment
that you’ll be limiting to just one area of the image. There are several ways of making a
secondary adjustment, but in this case you’ll do it using a Power Window, which is a shape you
can use to isolate the adjustment you’ll be making.