This tutorial will tells you to create a user online detection system. This tutorial has required a mysql database and php enable server.
Please follow these steps to complete your own UserOnline System.
Create table “user_online” in mysql in database “database1″.
CREATE TABLE `user_online` (
`userip` char(100) NOT NULL default ”,
`time` int(11) NOT NULL default ‘0’
) TYPE=MyISAM;