In your code, like in the function addon_name_content(), load the template file and execute it passing needed values:
```php
+use Friendica\Core\Renderer;
+
# load template file. first argument is the template name,
# second is the addon path relative to friendica top folder
$tpl = Renderer::getMarkupTemplate('mytemplate.tpl', __DIR__);
Hook::callAll('page_header', DI::page()['nav']);
Hook::callAll('nav_info', $nav);
+### src/Core/Authentication.php
+
+ Hook::callAll('logged_in', $a->user);
+
+### src/Core/StorageManager
+
+ Hook::callAll('storage_instance', $data);
+
### src/Worker/Directory.php
Hook::callAll('globaldir_update', $arr);