Frank, join a site like Photobucket.com or Flikr.com
Upload your picture to that site. They probably have an easy way for you to share them, but the manual method is to see the picture in your browser, copy the URL in the address bar and insert it between the IMG tags in the editor here.
Without spaces, it would be:
[ img ]http://www.melevsreef.com/pics/image.jpg[ /img ]
That's an example, and the URL doesn't link to an actual file called image.jpg - and don't forget: no spaces inside those brackets. I did that so you could see them in the example.