This link just takes you to a thread where renegade had attached the images. You've got to go one level further to get the image by itself.
If you 'right click' the picture and choose 'open image in new tab' (or similar depending on what browser you are using), it will open the image up all by itself and show it as a web address as below.https://www.24hourcampfire.com/ubbthreads/gallery/80/medium/102208.jpg
Notice how that ends in .jpg ?
put the [img]https://www.24hourcampfire.com/ubbthreads/gallery/80/medium/102208.jpg
[img] around it and it will post. For this line, i deleted the / in the last last img code so it would show what it should look like.