how to initialize session inside function of a script tag?

<?php
// Start the session
session_start();
?> 
 <script src="../../js/jquery.js"></script>
<script>
function hello(y){
              alert( y);
          }
</script>


 <?php 
 {


     require 'db_connect.php';
$count=0;
     $count = mysql_query ('SELECT COUNT(ques_no) FROM asg_cre_mcq') ;
     $row = mysql_fetch_array($count);
 //echo $count;
     for ($y = 1; $y <=$row[0]; $y++) 
     { 
           echo "<button   style='width:30px;height:30px' onclick='hello($y);'>". $y."</button>";
          // $_SESSION["buttons"] =$y;


         }
     } 
?>

I am dynamically generating buttons depending on the value coming from database. Then using onclick function I am performing check of click on button i.e. which button is clicked. what I want is to pass this vale of y i.e. button number to another php page in hello function using sessions. How can i do that?