I've found that the
Mozilla Developer Network is a good reference, btw, should you want to look things up.
In fact, I have a whole pile of bookmarks relating to webdev
:O One really nice one is
jsFiddle, which lets you experiment with HTML, CSS and/or JS (and a library like jQuery or Dojo) without having to set up a whole page to do so. It's great for trying out quick ideas.