Download this picture of my grandson Lucas, and save it on your computer. (Right click on the image and select Save Picture As to download the image).
Use an image processing program like Paint.net to create a 300 by 300 pixel image of just his face.
Adjust the brightness and contrast until it looks good, then crop and resize it to 300 by 300 pixels. Since the final photo will have a 1:1 aspect ratio, be sure to crop it to a square shape before resizing. Also, be sure to save it in storage and keep track of where you put it.
Print the image and its property sheet showing its size to turn in. (Right click on the link and select Properties to see the property sheet).
Note: the exact names of the commands to download the image and display its properties may vary depending upon your Web client.