intro to php question (SESSION)

[leetcrew]

intro to php

here's the flow of my webpage...

index.php
page1.php
page2.php
page3.php
page4.php
page5.php

page5.php

if ($HTTP_SESSION_VARS["log"] = false)
{
echo "

<script language='javascript'>
<!--

window.location.href('index.php?redirect=$SCRIPT_NAME');

//-->
</script>

";
}

visitors are required to log before they can open page1.php to page5.php.

Anyone pls do it for me... My purpose is just to study this code.
thanks in advance