From e-Learning Documentation
The Wiki is a tool that allows participants to collaborate together to create a webpage. Changes are tracked so it is possible to tell who contributed which aspects of the project. The Wiki tool requires users to adhere to a few simple formatting guidelines that are outlined in the tool for you.
You want to avoid having several people all trying to work on the Wiki at one time - This is not an "in-class activity." Since it is tracking changes, if there are several changes happening at once, the participants could be "overwriting" each other's work. The best scenario is that small groups work on the Wiki with a plan for who will post what, and when.
There is only one Wiki tool in your course, and you cannot add other Wikis, but you can add pages to your Wiki and direct each small group of users to their page where they will work together.
Add Content to the Wiki
Click Wiki in the left menu bar. When you first enter the Wiki, you will see a "Welcome" message about the Wiki tool and some possible uses for it, as well as some basic "getting started" information. You will want to read this text before you replace it with the content for your Wiki.
When you are ready to begin adding content to the Wiki, click Edit at the top of the page. The editing box appears with the default text in it. Notice A few formatting icons are across the top of the editing box - bold, italics, super and sub script, headings, tables, hyperlinks and images. "Wiki Tips" in the right margin provides Wiki formatting information for things like creating a new page and bulleted and/or numbered lists.