Nice explanations Brie and Hanne, you're right about Bandwith - some websites don't like people directly linking (or 'hotlinking) from the server, so I would suggest you get a Photobucket, or Imageshack account.
If you do want to directly link though, right click on the image, scroll down to 'Properties' and copy the link that comes up. That link should work within the [ img ] tags.
