create new functionality in modx manager

<?php
$basePath = dirname( dirname( dirname( dirname( __FILE__ ) ) ) );
require_once $basePath . '\config.core.php';
require_once MODX_CORE_PATH . 'config/' . MODX_CONFIG_KEY . '.inc.php';
require_once MODX_CONNECTORS_PATH . 'index.php';
$modx->request->handleRequest( array(
    'processors_path'   => $modx->getOption( 'core_path' ) . 'components/mycomponent/processors/',
    'location'          => ''
) );
?>
<?php
return $modx->smarty->fetch( '/path/to/templates/list.tpl' );
$modx->smarty->assign( '_lang', $this->modx->lexicon->fetch() );
?>
<h2 class="modx-page-header">{$_lang.mycomponent}</h2>

<?php
$o = '<div class="test"><h2>My Component</h2></div>';

return $o;
?>

Notice: Constant MODX_CORE_PATH already defined in D:\xampp\htdocs\paragon\config.core.php on line 2

Notice: Constant MODX_CONFIG_KEY already defined in D:\xampp\htdocs\paragon\config.core.php on line 3

Notice: Undefined index: action in D:\xampp\htdocs\paragon\core\model\modx\modconnectorrequest.class.php on line 61
{"success":false,"message":"Access denied.","total":0,"data":[],"object":{"code":401}}

<?php
return 'This is my first Custom Manager Page';
?>

$query=mysql_query("select * from modx_menus");
while($query_res=mysql_fetch_array($query))
{
    echo $query_res['text'];
}