Add first the last jQuery release, then the jQZoom script(don't forget this),the correct order is important.Look at the installation code below.

<script type='text/javascript' src='js/jquery-1.2.6.js'></script>
<script type='text/javascript' src='js/jquery.jqzoom-1.0.1.js'></script>

Add jqzoom.css to your header.

<link rel="stylesheet" type="text/css" href="css/jqzoom.css" />

Using jQZoom is easy,but you need to specify the HTML anchor element,that is going to generate the zoom revealing a portion of the enlarged image.

<a href="images/BIGIMAGE.JPG" class="MYCLASS"  title="MYTITLE">
<img src="images/SMALLIMAGE.JPG" title="IMAGE TITLE"  >
</a>

The anchor element wraps the small image you would like to zoom.Following this schema the necessary and base elements are:

SMALLIMAGE.JPG: Represents the small image you would like to zoom.
BIGIMAGE.JPG: Represents the big image that jQZoom will reveal.
MYCLASS: Represents the anchor class,that would be used to instantiate the jQZoom script to all the elements matching this class(you can use an ID as well).
MYTITLE/IMAGE TITLE: Anchor title and/or image title that will be used to show the zoom title close to the jQZoom Window.

Now load the plugin at window load.

$(document).ready(function(){
 $('.MYCLASS).jqzoom();
});

This would instantiate jQzoom in default(standard) mode.You can pass more options(Documentation section),to create special or custom effects as in the example below.

$(document).ready(function(){
 var options = {
     zoomWidth: 300,
     zoomHeight: 250,
            xOffset: 10,
            yOffset: 0,
            position: "right" //and MORE OPTIONS
};
 $('.MYCLASS).jqzoom(options);
});