MediaWiki cheat sheet - janosgyerik/cheatsheets GitHub Wiki
How to ...
Edit links in the sidebar
You can do this on the special page called MediaWiki:Sidebar. To get to this page, search your wiki for "sidebar", then in Advanced Search tick the MediaWiki namespace.
Text formatting is documented on http://meta.wikimedia.org/wiki/Help:Wikitext
In some MediaWiki skins, when you are logged in and want to edit some text, there is no Edit button for the pages themselves, only for page sections. An easy workaround is to go to your preferences and enable page editing by double-click.