Select a project and click on the Wiki tab.

1 If you set a wiki page as "Wiki menu" the page will appear on the left side of your screen and can be used as a menu. You could use the Wiki menu as an index of contents or list all categories of wiki pages.

2 To set and unset a wiki page as "Wiki menu" click on the list icon in front of any wiki page.

See also: How to link pages? and How to insert a Table of Contents?