So, upload there and then copy the address in the source field?
Right, that's because the link you are linking isn't the image itself, but a webpage.
Navigate to that webpage, and then click on the image. Clicking on the image will take you to the address of teh image itself, and then you can use that address.
The address you will need to use is: http://i.imgur.com/ZFp3Jy0.jpg?1