First, you must find the aerial photo you wish to overlay. That may not be easy. Check your state's website. When you find the picture you want, save it on your computer. Then, in G.E., use the Overlay (icon) button to bring up the overlay function, click Browse to find the pic you stored and select it. It will appear on G.E. You will have to adjust the size, position, and orientation of the overlay to make it match the G.E. image.
Pete