<?php

if (isset($_REQUEST['tab'])):
	$tab = $_REQUEST['tab'];
	if ($tab == 4)
		{
		echo '4th Tab Content';
		}
	elseif ($tab == 3)
		{
		echo '3rd Tab Content';
		}
	elseif ($tab == 2)
		{
		echo '2nd Tab Content';
		}
	  else
		{
		echo '1st Tab Content';
		}
	else:
?>

HTML and Javascript codes here

<?php
	endif; ?>