If you look at the top of your browser you will see a location box with http://www.foreverspades.com/tdcenter/urlinfo.htm. .That is the URL of this page.
A URL is the place on the internet where your image is stored. When someone brings up an tourney page the HTML codes will fetch the picture from where you stored it. I use my server at www.foreverspades.com to store my images. If I uploaded an image from there the URL would be http://www.foreverspades.com/NAME OF PICTURE.jpg. Make sure your image ends in .jpg or .gif and that you have NO spaces in your URL. URL's are case sensitive, A is not the same as a.

There are a couple links for free hosting sites for your images on the main page of the TD Help Center.