A WikiWikiWeb is a collaborative hypertext environment, with an emphasis on easy access to and modification of information.
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. Pages which do not yet exist are linked with a question mark or in bold red; 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 Wiki:WikiWikiWeb is, read about Wiki:WhyWikiWorks and the Wiki:WikiNature. Also, consult the Wiki:WikiWikiWebFaq and Wiki: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: search or browse the database in various ways
TitleIndex: a list of all pages in the wiki
WordIndex: a list of all words that are part of page title (thus, a list of the concepts in a wiki)
SiteNavigation: a page leading to the different indexing schemes of the wiki
WikiSandBox: feel free to change this page and experiment with editing
HelpOnEditing: the starting point to learn everything about wiki markup