The picture hasta be on th web, Lash, with its own URL - in your machine ain't gonna do it for ya, and ya gotta use the URL of the image itself.
As an example, right click on your own avatar image, select "Properties", and note that in the "Properties" box, it says
That's the actual URL of the image itself, which is whatchya want. Whatchya been doin, however, is tryin' to use not the URL of an image, but rather the URL of the location of some images. You can bring that page up in your browser, and it will display an image. If you'll right-click that image and select "Properties", you'll get the URL for that particular image. Even easier however, in this case, is just to look in your browser's address bar; it'll have the url of the displayed image. Just click in the address bar to highlight the URL, copy it, and paste it between the
tags.
Goin' back to the example of your own avatar, click this:
http://www.able2know.com/forums/images/avatars/gallery/celebrities/ki01.gif
You'll be taken to the image itself, which will be a small picture in the upper LH corner of your browser. Note that if you right click on the actual image and select "Properties", the result will be the same as what's displayed in your browser's address bar.