getting problem in older version of opencart

hii
i am getting some errors in opencart 1.5.5 or below at the top of my front end and in backend i am getting this error "Deprecated: mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in /home/u320435096/public_html/system/database/mysql.php on line 6
"
please tell me what to do

find mysqliz
http://www.opencart.com/index.php?route ... n_id=13041

chamge configs

define('DB_DRIVER', 'mysqliz')