How to expire a Session ?

Hello there... I would like to know how to set the session timeout time
locally and not globally in the php.ini file.
I do that as it is ine www.php.net but doesn't seem to do anything
/***************************/
/* set the cache limiter to 'private' */

session_cache_limiter('private');
$cache_limiter = session_cache_limiter();

/* set the cache expire to 1 minutes */
session_cache_expire(1);
$cache_expire = session_cache_expire();
/******************************/
I enter 1 minute for testing purposes....
- Also It would be helpfull to let me know how I am going to verify that
the session has been expired....
- Is there any way to automatically refresh the page when the session has
expired and let the user know ?
- Is there any good site that I can find tutorials or examples for this
purpose?
< - > Thank you !!!< /- >