Creating left hand menu in admin component

The right hand menu that often appears in admin components is configured in the /com_name/helpers/name.php file.

For example:

public static function addSubmenu($submenu)
    {
        JSubMenuHelper::addEntry(
            JText::_('COM_REGCAN_SUBMENU_CANSKATESESSIONS'),
            'index.php?option=com_regcan&view=organizers',
            $submenu == 'canskatesessions'
        );

                JSubMenuHelper::addEntry(
            JText::_('COM_REGCAN_SUBMENU_MESSAGES'),
            'index.php?option=com_regcan',
            $submenu == 'messages'
        );

        JSubMenuHelper::addEntry(
            JText::_('COM_REGCAN_SUBMENU_CATEGORIES'),
            'index.php?option=com_categories&view=categories&extension=com_regcan',
            $submenu == 'categories'
        );

        // set some global property
        $document = JFactory::getDocument();
        $document->addStyleDeclaration('.icon-48-regcan ' .
                                       '{background-image: url(../media/com_regcan/images/tux-48x48.png);}');
        if ($submenu == 'categories')
        {
            $document->setTitle(JText::_('COM_REGCAN_ADMINISTRATION_CATEGORIES'));
        }
    }