Adobe Illustrator CC Classroom in a Book (2019 Release), First Edition

Choose View > Zoom Out.

With the Selection tool selected, drag the water image into the center of the artboard. Make
sure the bottom of the image is aligned with the bottom of the artboard.

Select the Rectangle tool ( ) in the Tools panel, and click in the approximate center of the
artboard. In the Rectangle dialog box, make sure the Constrain Width And Height Proportions
is off ( ), change Width to 9 in and Height to 8 in. Click OK. This will become the mask.