Help:Editing
From Graphene Theme Documentation
Wiki formatting and examples
Wikis use special markup to format contents. If you're not familiar with the wiki markup, here's a few good primer links:
Editing permission
Everyone is permitted to create and edit pages, including anonymous users. However, a captcha will be displayed before you're able to save the page to deter spam. To get rid of the captcha, simply register an account since captcha will not be served to registered users.