Help:Contents - Tips for basic formatting/organization.
Help:Editing - Tips for basic and advanced editing, including table creation, using formulas, etc. This link is at the bottom of your editing screen - near the Save page button.
Wiki Help: Adding Media - Tips for adding media: images, video and flash files
Documentation:MediaWiki_Basics/Hands_On:_6_Things_To_Know - For some hands on activities to try some editing in our Sandbox.