Wiki software is not available on the School of Earth, Energy & Environmental Sciences web server. It is recommended that school groups use the service provided by the University.
To install the wiki, make sure you're logged in and then select "Get this service". That will bring you to a page where you can select "mediawiki" under "Select an application" and your group space under "Select cgi-bin space".
Note: If you don't see anything listed under cgi-bin space, you'll need to request space from ITS.