Use the page Special:Allpages to get a list of all pages (articles) contained within the wiki. You will find it in the list of Special pages, which you can ready from the Toolbox to the left of every page.
When the list of articles is very large it can be useful to use the control at the top of the page to list only articles at or after a given article name.
The articles (pages) which make up the content of the wiki are in a default namespace called "(Main)". Other supporting pages are in other "namespaces", such as "Talk", "User", "UserTalk", "Help", "Templates", and "Category". You can also use this special page to view a list of all the pages in those special namespaces.