Changing links by changing vars

[Tekton]

It doesn't really bother me much if it's empty as it would do what I want anyways. :P
*goes off to try new help things*

UPDATE : Got it working with something like...

<script type="text/javascript">
function change_b8()
{
    num_8 = document.poop.b8.value;
}
</script>

and

 
<a href="javascript: window.location = 'http://www.site.com/blah.php?do=blah&amount=' + num_8;">[Buy]</a>