how to create popup terms and conditions in opencart

If you have custom footer module, you can put the code below :

<ul class="list">
    <li ><a class="colorbox" href="index.php?route=information/information/info&amp;information_id=4">About Us</a></li>

    <li><a class="colorbox" href="index.php?route=information/information/info&amp;information_id=3">Privacy Policy</a></li>

    <li><a class="colorbox" href="index.php?route=information/information/info&amp;information_id=5">Terms &amp; Conditions</a></li>
</ul> 


don't forget to put this script in footer.tpl of your theme.
 
<script type="text/javascript">
<!--
$(document).ready(function() {
    $('.colorbox').colorbox({
        width: 750,
        height: 550
    });
});
//-->
</script>