public function actions()
    {
        return [
    'auth' => [
      'class' => 'yiiauthclientAuthAction',
      'successCallback' => [$this, 'oAuthSuccess'],
    ],
  ];
    }
public function oAuthSuccess($client) {
  // get user data from client
        $userAttributes = $client->getUserAttributes();
        return $this->render('say',['first_name' => $userAttributes['first_name'],'last_name' => $userAttributes['last_name'], ]);
  // do some thing with user data. for example with $userAttributes['email']
}

<?php
use yiihelpersHtml;
?>
<?= Html::encode($first_name) ?>
<?= Html::encode($last_name) ?>