Here is one I just sent a friend to explain the same process:
I found it in a copyright free site just of backgrounds to use. Since the image will show up in the post you see, I can just tell you that when I inserted it in this post, I clicked on "IMG" in the toolbar of this textbox, then a window popped up and I used <control+V> to paste in a long, long, 4 line properties URL from the public msn.com site I use for posting images.
My post looks to me like a long long html code, starting [IMG]http://groups.msn.com/_Secure/ORwAaAOcWRTrHkpj8AEd etc. and it is a jpg image. jpgs and gifs work this way here.
Hope this helps! To get that URL for the image only properties (not the web page URL), you right click on a posted image and a box comes up to list it for you. Use <control+C> to highlight and copy the WHOLE URL and then you are ready to come back into the post to link it in.