A tutorial for beginners on Wiki(p|m)edia. Also applies to our wiki here.
Lean how to edit pages:
http://en.wikipedia.org/wiki/Wikipedia:Tutorial
More editing details:
http://en.wikipedia.org/wiki/Wikipedia:How_to_edit_a_page
Wiki Markup:
http://en.wikipedia.org/wiki/Wikipedia:How_to_edit_a_page#Wiki_markup