To make the tool active, click it. The center of the tool turns red to let you know that it’s active (as shown in Figure 2). Take the tool and click-and-drag a selection around one of the red eyes. I’m using the term selection, but it’s not really a "selection" in the Photoshop sense—it’s more a box with a solid line. As soon as you drag the selection outward, Lightroom removes the red eye. If it doesn’t remove all of the red, you can expand the selection by dragging the Pupil Size slider to the right (circled in red in Figure 2).