A WikiWikiWeb is a collaborative hypertext environment, with an emphasis on easy access to and modification of information.
To edit the Ubuntu Wiki, join the Ubuntu Wiki Editors team on Launchpad.
You can edit any page by pressing the "edit" link. Depending on the selected user interface theme you may find this at the top, in the sidebar area or at the bottom of the page. Capitalized words joined together form a WikiName, which hyperlinks to another page. Clicking on the highlighted title searches for all pages that link to the current page. Links to pages which do not yet exist have different text color (usually gray) or have a question mark; just follow the link and you can add a definition. That is also the way to create a new page: add a new WikiName to an existing page, save your modification, click on your new link and create the page (more details on HelpOnPageCreation).
You are encouraged to edit the WikiSandBox whichever way you like. Please restrain yourself from editing other pages until you feel at home with the ways a wiki works.
To learn more about what a WikiWikiWeb is, read about WhyWikiWorks and the WikiNature. Also, consult the WikiWikiWebFaq and OneMinuteWiki. This wiki is also part of the InterWiki space, which means you can easily refer to a wealth of information available through other public wiki sites.
Good starting points to explore a wiki are
RecentChanges: see where people are currently working
FindPage: find some content or explore the wiki
WikiSandBox: feel free to change this page and experiment with editing
HelpOnEditing: the starting point to learn everything about wiki markup