You use the auth manager assign function to give users access to an auth item. See http://www.yiiframework.com/doc/api/1.1/IAuthManager#assign-detail
E.g.
Yii::app()->authManager->assign('createPage', $idOfMyUser);
You can then use the access rules in a controller to control who can perform an action
Like:
public function accessRules()
{
array('allow',
'actions' => array('create'),
'roles' => array('createPage')),
array('deny'),
);
}
Note that Roles, Operations and Tasks are essentially the same thing, they are just a ways of seperating or groping auth items