try this javascript function which will be called with php code
add this code in your inside the head tag but below the title tag
<script type="text/JavaScript">
<!--
function MM_openBrWindow(theURL,winName,features) { //v2.0
window.open(theURL,winName,features);
}
//-->
</script>
and this code you will add it inside the body tag, but you have to first test if the cookie is not set. if not set thats when you put this code
<?php echo"<SCRIPT LANGUAGE='JavaScript'> MM_openBrWindow('yourpage.html','advert','status=yes,resizable=yes,width=500,height=400')</SCRIPT>";
where it says:
your page- put the name of the page you want to be popped
advert- just the name you want to give it
status- is if you want it to show status bar
resizable- is when you want it to be resizable
width and height- thats the size of the pop up
Unsolved 
