Looked at your site and did not see any html for reference.
Head & body tags per se are not there for editing as in php the actual page is constructed dynamically.
You should start with includes/templates/template_default/sideboxes/tpl_categories.php and includes/language/english.php and insure that any edited file is placed into another folder that is inline with the override functionality of Zen Cart. This example is for the categories box:
In the tpl_categories.php file find and replace with this.
Code:
zen_image($template->get_template_dir($box_categories_array[$i]['name'] . '.gif', DIR_WS_TEMPLATE, $current_page_base,'images'). '/' . $box_categories_array[$i]['name'] . '.gif', $box_categories_array[$i]['name'])
If you want to do rollovers, with javascript, or the CSS clipping method, you can add extra info the <img> tag along this line:
Code:
zen_image(image source file name, alt text, width, height, other parameters)
Images are defined for the boxes in place of the text descriprion in the english.php file like for categories:
Code:
define('BOX_HEADING_CATEGORIES', 'your_graphic.jpg');