A more general tip that you can use on several different message boards is to quote a post that is doing what you want to do. You will generally see all of the markup that was used. I admit that it is not always the fastest way (you still have to find a post with a spoiler/image/video/footnote), but it works very well and in a lot of different forums. Try it!
Here is an image:
And a footnote[footnote]awesome![/footnote].
Also, on this and a couple of other sites, most of the markup tags are inspired by HTML, so you can just look up a reference [http://htmldog.com/reference/htmltags/] and see how what you want is accomplished in HTML and then try it here (with square brackets instead of ). It doesn't always work, but that's what the preview button is for.
