How do you insert a jump menu for categories on a wp page

How do you insert a jump menu for categories on a wp page.

If I wanted to have a jump menu on a page showing all the categories or sub-categories, can this be done?

I tried html code but there is a js script in the <head> that I don't know where that goes on a wp page, or if it goes in another file like the functions.php? Below is the html and js code I am trying to use. However if there is an easier way then please advise. Thanks.

NOTE: not all the variables are included like the URL link, this is just an example. Also note that when I tried it of course the links didn't work because the javascript was missing.

'<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Untitled Document</title>
<script type="text/javascript">
function MM_jumpMenu(targ,selObj,restore){ //v3.0
eval(targ+".location='"+selObj.options[selObj.selectedIndex].value+"'");
if (restore) selObj.selectedIndex=0;
}
</script>
</head>

<body>

<form name="form" id="form">
<select name="jumpMenu" id="jumpMenu" onChange="MM_jumpMenu('parent',this,0)">
<option value="vvv">item1</option>
</select>
</form>
</body>
</html>
'