Looking at your post some more I guess the real question is how do you want it to work.
Currently you are posting a image in a gallery forum. Then creating a island that displays the contents of the gallery forum.
For that to work you will need to provide a link in the description of the gallery post.
If you wish to have the image display in a island then when a visitor selects the image to goto the sponsors site then the example provided above would work.
