Here is solution of my question .

If you have issue with smarty root directory issue , you can use this, It's hundred percent working.

Thanks @ADyson

use Smarty\Smarty;
$smarty = new Smarty();
$smarty->setTemplateDir(__DIR__ . '/templates');
$smarty->setCompileDir(__DIR__ . '/templates_c');
$smarty->setCacheDir(__DIR__ . '/cache');
$smarty->setConfigDir(__DIR__ . '/cache');