Here's a short complete html example. See demo http://jsfiddle.net/CU585/
<!DOCTYPE html><html><head><title>resizable columns</title>
<meta charset="utf-8">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.0/themes/smoothness/jquery-ui.css" />
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.0/jquery-ui.min.js"></script>
<style>
th {border: 1px solid black;}
table{border-collapse: collapse;}
.ui-icon, .ui-widget-content .ui-icon {background-image: none;}
</style>
<body>
<table>
<tr><th>head 1</th><th>head 2</th></tr><tr><td>a1</td><td>b1</td></tr></table><script>
$( "th" ).resizable();
</script></body></html>