Click 
.
Position the cursor over the image and click and drag diagonally to create a box. The highlight box is displayed on the image, and nodes mark each corner.
Enhancing Images > Using the Tool Box Toolbar > Using the Drawing Tools
Use the Highlight tool to draw a transparent colored box to emphasize an area of interest in an image.
To add a highlight box:
Click .
Position the cursor over the image and click and drag diagonally to create a box. The highlight box is displayed on the image, and nodes mark each corner.
To change the properties of this tool, use the Annotations Properties toolbar. See Changing Annotation Properties for more information.