The old RedPhir used something called BBCode to format post content. The new way of the world around here is called "Markdown."
I'll go over a couple quick instructions below, but if you want to know more, here is a more detailed set of detailed instructions you're invited to read through.
There are some formatting buttons above the composer window that help (bold, italics), some that are broken (underline), some even I'm confused by (video options) and there doesn't appear to be one for embedding images.
So, here are the direct instructions that don't require buttons.
[I'm an inline-style link](https://www.google.com)
![These are the panties poster Keith asked the audience to stop throwing at him on stage at the 930 Club](http://dcshows.net/photos/a_20040702_930_Club-Daycare_Swindlers_Last_Show/DCS20040702SB-037.jpg)
The text in between the  is called "image alt text" (what appears when you hover your cursor over an image, in most browsers) and can be left blank, so long as you leave the  in place:
This isn't markdown, but a plugin that works better.
I want to embed this video: http://www.youtube.com/watch?v=s2p0ajIHovk
You'll need to know that s2p0ajIHovk is the Youtube video ID, aka keyword.
The code to embed the video is as such:
Which results in:
Quoting is simple. Begin your line with a greater-than symbol and a space.
> This is a quote
This is a quote.