There are substantial rules for editing and creating articles on wikipedia, covering a range of aspects of that work.
However, to get started, Wikipedia has five pillars that summarise working with Wikipedia
For more detailed explanation of the five pillars, go to the Wikipedia Five pillars page
As Wikipedia is largely composed of volunteers, and anyone can access the site and make changes, it needs complex rules about creating pages.
Wikipedia has a range of policies on aspects of editing the site, covering bias, point of view, copyright, civility, spin, style, the encyclopedic nature of the source and many others. Different rules apply for different pages, for instance, rules for biographical pages for people that are alive are different compared to those for historical figures.
To see a summary of the wikipedia rules, go to the Wikipedia Guidelines summary on the University of Melbourne Wiki Editing Community
To see the wikipedia guidelines in full, go to the Wikipedia guidelines on the Wikipedia site.