New to jquery plugins

New to jquery plugins

Hi -  I'm extremely new to jquery plugins and I'm having a hard time trying to go through a few examples of the current book I'm reading in order to get them to work.  If anybody could point me in the right direction well just explain how plug ins work and are called that would be great.  What did I do wrong because I'm just not seeing it.

<script type="text/javascript" src="jquery library/jquery.colorbox.js"></script>
<link type="text/css" media="screen" rel="stylesheet" href="css library/colorbox.css">
<script type="text/javascript" src="jquery library/jquery.js"> </script>

<script type="text/javascript">
$(document).ready(function()
{


$(‘a’).colorbox();


});
</script>

</head>

<h1>Replacing</h1>

<body>


<a href=”content/daisy.jpg”> Click me </a> .......


Thanks

Troy