The code looks like this:
**[/img ][/url ]
Where * is the URL of the page you want to click through to (the photo page with the “all sizes” etc. buttons at the top)
and ** is the URL of the photo itself (from option 2 on the “all sizes” page)
Remove all spaces, send post!
You made it more complicated than you need to..
The “all sizes” page has some HTML code above the JPG link, I’d switch to medium or small size first. Just copy and paste that.