1. Take full image link
Code:
http://img10.hostingpics.net/pics/614407DukeUI30.jpg
2. Replace "pics" with "thumbs". Add "mini_" in front of the file name.
Code:
http://img10.hostingpics.net/thumbs/mini_614407DukeUI30.jpg
3. Put [img] tags around the thumbnail URL.
Code:
[img]http://img10.hostingpics.net/thumbs/mini_614407DukeUI30.jpg[/img]
4. Add [url=full link][/url] tags.
Code:
[url=http://img10.hostingpics.net/pics/614407DukeUI30.jpg][img]http://img10.hostingpics.net/thumbs/mini_614407DukeUI30.jpg[/img][/url]
5. Done.


Thanks to whoever I stole that screenshot from.