Formatting, editing, and creating WikiPages is a little different than standard HTML, although you can actually include all the HTML you know. Check out the following external links for various topics:
For help on your USER PAGE, see Help:User_page
A cheat sheet containing some of the above can be found here.
The tutorial is a good place to start.
The most frequent wiki markup explained.
Lots of examples.
Info on Project organization within the wiki.