1) Read the user manual! for PHP 4.3.1 on Sessions.
2) Here is some code:
Put this at the top of your page...
<?php session_start(); ?>
Then where ever you will be setting session variables just assign them like this:
if (!isset($_SESSION['mysession'])) {
$_SESSION['mysession'] = session_id();
}
$thissession=$_SESSION['mysession'];
3) Search this FORUM for $_SESSION and I am sure you will find plenty of examples on how to use sessions...