When you want to override the edit permissions of an area but you don't want to use Advanced Permissions, just use the following code:

$a = new GlobalArea('My_Site_Name'); 
$u = new User();
if (!$u->isSuperUser())
 $a->showControls = false;
$a->display(); 

In this case only the Super User is allowed to edit the Area in the frontend. To create a own filter with user, groups or groupsets check this page: http://www.concrete5.org/documentation/developers/permissions/users/

Hope this helps!

Best,

Corretje