Go to the View pull down menu on your browser and click on Source.
Then scroll down to look for someone else's numbered post that had a picture or link and copy it to paste to your reply.
Just substitute your URL link or picture location in place of what they had posted.
You can use this to learn how someone did an interesting effect or formatting trick.
The thing I find myself wishing for is the ability to link to a specific reply within a thread other than the one I'm posting in. You'd think that viewing the source code of a thread would reveal the trick to that - every reply to the first reply has a "TO 1" button, after all - but I haven't had any luck trying it.