<?php 
defined('C5_EXECUTE') or die(_("Access Denied."));
?>
<form method="post" action="<?php echo $controller->action('save') ?>">
   <h1><?= t("Microsite Theme") ?></h1>
    <div class="form-group">
       sdvsdvdssdv
    </div>  
</form>

<?php
namespace Application\Controller\SinglePage\Dashboard;
use \Concrete\Core\Page\Controller\DashboardPageController;
class MicrositeTheme extends DashboardPageController {
    public function on_start(){
      $this->set('pageTitle','Theme');
    }
    public function view(){
       $this->set('message', 'Test Message');
    }      
}