Groups

I set up a “test” domain to test the use of software, rights, permissions etc. I have a “user” who needs to be in the Everyone group. When I try to locate the Everyone group, it doesn’t show up in the Built-in Groups. When I try to create the group I get an error message that says the group can’t be created because it already exists. When I do a search for the group, it can’t be found. Any suggestions??