i will try everything you tell

which chmod should i use and to which file?

really appreciate you followed my thread

or do i need to change anything on geshi.php ?

 
/ Define the root directory for the GeSHi code tree
if (!defined('GESHI_ROOT')) {
    /** The root directory for GeSHi */
    define('GESHI_ROOT', dirname(__FILE__) . DIRECTORY_SEPARATOR);
}
/** The language file directory for GeSHi
    @access private */
define('GESHI_LANG_ROOT', GESHI_ROOT . 'geshi' . DIRECTORY_SEPARATOR);
 
// Define if GeSHi should be paranoid about security
if (!defined('GESHI_SECURITY_PARANOID')) {
    /** Tells GeSHi to be paranoid about security settings */
    define('GESHI_SECURITY_PARANOID', false);
}