Looking on the web to find a good tutorial for implementing an auth system with Pear Auth(). I need to use different user permission, storing access level in a db field. On the official docs can't find anything about permission level...
Authentication is signifying that you own an identity. This is what PEAR Auth does.
Authorization is signifying that an identity has permission to perform an action.
Authentication is not authorization.
Take a look at this previous question on good ACL classes, which you can use to perform Authorization.