hiding div tag when the if condition meets

hiding div tag when the if condition meets

I am trying to hide a <div> tag when my my data is zero...
i have if condition
if ($_SESIION['m1']==0)
{
I want the tag to be de-activated and this is my <div> tag
<div class="right"><a href="<?php echo $checkout; ?>" class="button"
id="checkout"><?php echo $button_checkout; ?></a></div>
else
the <div> should be activated..
I really dont know how to achieve this.