SurveyWiki uses exactly the same content management system as Wikipedia. So, learning how to edit content on SurveyWiki, is exactly the same as learning to do it on Wikipedia. Most of the links below will take you to Wikipedia help pages and you can simply apply what you learn there to SurveyWiki. A few pages are specific to SurveyWiki.
The SurveyWiki interface
Find your way around.
Experiment with editing pages in the sandbox. You can also carry out editing experiments "in situ" by editing the page itself and using the Show preview button. Be careful not to accidentally save the page though! If you do, then revert your changes.