Like user information, accessing global configuration of Joomla (like site name, from name) is very simple process. You can use getConfig function of JFactory class in any part of Joomla extension or template.

$config = JFactory::getConfig();

For example, site name stored in global configuration can be retrieved as

$config->get('sitename')

Similarly, from name can be retrieved as

$config->get('fromname')

You can check configuration.php file stored in root Joomla folder for all the global information that can be accessed in this way.