Joomla! Documentation™

Edit your /includes/defines.php file. Below is the relevant code.

define( 'JPATH_ROOT' , implode( DS, $parts ) );
define( 'JPATH_SITE' , JPATH_ROOT );
define( 'JPATH_CONFIGURATION', JPATH_ROOT );
define( 'JPATH_ADMINISTRATOR', JPATH_ROOT . DS . 'administrator' );
define( 'JPATH_LIBRARIES' , JPATH_ROOT . DS . 'libraries' );
define( 'JPATH_INSTALLATION' , JPATH_ROOT . DS . 'installation' );