Question for the Wiki maintainers

[thephotoman]

Well, I'm working on a wiki for a personal project.  However, due to the 
nature of the project, the intended audience is only a handful of 
people.  It's dealing with the day-to-day operations of a non-profit 
entity.  We're using WikiWiki to coordinate efforts, as we're based 
online, and use volunteers from all over the world to run our operations.

What I need to know is how to make it so that only registered users who 
have been approved by the administrators of the wiki are the only ones 
who are able to make edits.

Thanks for your help!