class My_Block extends Mage_Adminhtml_Block_Template { public function __construct() { parent::__construct(); $this->setTemplate('my/template.phtml'); $this->setData('my_data', 'Hello World'); } // Other methods here }In this example, we extend the Mage_Adminhtml_Block_Template class and set the template path and some custom data using the setData() method. Package library: Magento PHP Library.