User blog:Orion001/Paranormal Witness Wiki

I need user for Paranormal Witness Wiki. But there is a but in this. I do not need unregistered users. You the show was meant for teenagers from 13 and up. And the show is for a mature audence because the stories may scare or shock sensitive users. So my biggest problem is if a unregistered in is under the age limit. So I need a program to prevent unregistered user to edit the site. I prefer registered user because than I know they are over the age limit since only people 13 and over are allowed to edit on wiki sites. So please anyone help me.