A template is a predefined piece of HTML that can be applied to the editors editing area. By default the editor comes with three sample templates which can be modified
fitting the end users needs. These templates can be created and changed by simply modifying the default.js file found at:-

/public_html/plugins/editors/jckeditor/plugins/templates/templates/default.js

You can create and define your templates by simply adding your custom HTML code to the default.js file as detailed below:-

{
        title: 'Image and Title',
        image: 'template1.gif',
        description: 'One main image with a title and text that surround the image.',
        html: '<h3><img style="margin-right: 10px" height="100" width="100" align="left"/>Type the title here</h3><p>Type the text here</p>'
    }

Example file:-

/*
Copyright (c) 2003-2010, CKSource - Frederico Knabben. All rights reserved.
For licensing, see LICENSE.html or http://ckeditor.com/license
*/

CKEDITOR.addTemplates('default', {
    imagesPath: CKEDITOR.getUrl(CKEDITOR.plugins.getPath('templates') + 'templates/images/'),
    templates: [
    {
        title: 'Image and Title',
        image: 'template1.gif',
        description: 'One main image with a title and text that surround the image.',
        html: '<h3><img style="margin-right: 10px" height="100" width="100" align="left"/>Type the title here</h3><p>Type the text here</p>'
    },
    {
        title: 'Strange Template',
        image: 'template2.gif',
        description: 'A template that defines two colums, each one with a title, and some text.',
        html: '<table cellspacing="0" cellpadding="0" style="width:100%" border="0"><tr><td style="width:50%"><h3>Title 1</h3></td><td></td><td style="width:50%"><h3>Title 2</h3></td></tr><tr><td>Text 1</td><td></td><td>Text 2</td></tr></table><p>More text goes here.</p>'
    },
    {
        title: 'Text and Table',
        image: 'template3.gif',
        description: 'A title with some text and a table.',
        html: '<div style="width: 80%"><h3>Title goes here</h3><table style="float: right" cellspacing="0" cellpadding="0" style="width:150px" border="1"><caption style="border:solid 1px black"><strong>Table title</strong></caption></tr><tr><td>&nbsp;</td><td>&nbsp;</td><td>&nbsp;</td></tr><tr><td>&nbsp;</td><td>&nbsp;</td><td>&nbsp;</td></tr><tr><td>&nbsp;</td><td>&nbsp;</td><td>&nbsp;</td></tr></table><p>Type the text here</p></div>'
    }]
});

For more information on this topic please see the cksource documentation: http://docs.cksource.com/CKEditor_3.x/Developers_Guide/Templates