You must create themes in the /public/themes/ folder.
All themes must include an index.temlplate.php file to define the HTML structure of the theme.
You can seperate your theme on footer and header with help of chunks.


Theme structure

 theme/
  ├── css/
  │   ├── theme.css
  ├── js/
  ├── img/
  ├── header.chunk.php
  ├── footer.chunk.php
  └── index.template.php

Simple Example


header.chunk.php

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title><?php echo Site::name() . ' - ' . Site::title(); ?></title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">       
<meta name="description" content="<?php echo Site::description(); ?>">
<meta name="keywords" content="<?php echo Site::keywords(); ?>">
<meta name="robots" content="<?php echo Page::robots(); ?>">
<!-- Styles -->
<?php Stylesheet::add('public/assets/css/bootstrap.css', 'frontend', 1); ?>
<?php Stylesheet::add('public/themes/theme/css/theme.css', 'frontend', 2); ?>
<?php Stylesheet::add('public/assets/css/bootstrap-responsive.css', 'frontend', 3); ?>
<?php Stylesheet::load(); ?>
<?php Action::run('theme_header'); ?>
<!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
<!--[if lt IE 9]>
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<!-- Fav icons -->
<link rel="icon" href="<?php echo Site::url(); ?>favicon.ico" type="image/x-icon">
<link rel="shortcut icon" href="<?php echo Site::url(); ?>favicon.ico" type="image/x-icon">
</head>
<body>
<div class="navbar navbar-fixed-top">
<div class="navbar-inner">
  <div class="container">
    <a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
      <span class="icon-bar"></span>
      <span class="icon-bar"></span>
      <span class="icon-bar"></span>
    </a>
    <a class="brand" href="<?php echo Site::url(); ?>"><?php echo Site::name(); ?></a>
    <div class="nav-collapse collapse">
      <ul class="nav">
          <?php echo Menu::get(); ?>
      </ul>
      <div class="pull-right user-panel">
        <?php Users::getPanel(); ?>
      </div>
    </div><!--/.nav-collapse -->
  </div>
</div>
</div>

index.template.php

<?php Chunk::get('header'); ?>
<div class="container">
<div>
<?php Action::run('theme_pre_content'); ?>
</div>
<div>
<?php echo Site::content(); ?>
</div>
<div>
<?php Action::run('theme_post_content'); ?>
</div>
<hr>
<?php Chunk::get('footer'); ?>   

footer.chunk.php

<footer>
<p>                      
<div style="float:right;"><?php Action::run('theme_footer'); ?><?php echo Site::powered(); ?></div>
</p>            
</footer>
</div> <!-- /container -->
<!-- Javascript
================================================== -->
<!-- Placed at the end of the document so the pages load faster -->
<script type="text/javascript" src="<?php echo Option::get('siteurl'); ?>public/assets/js/jquery.js"></script>
<script type="text/javascript" src="<?php echo Option::get('siteurl'); ?>public/assets/js/bootstrap.js"></script>
<?php Javascript::load(); ?>
</body>
</html>