Another new book has been published about OpenCart:

Here is the description:

• Customize dynamic menus, logos, headers, footers, and every other section using tricks you won't find in the official documentation

• A great mix of recipes for beginners, intermediate, and advanced OpenCart template designers

• Develop and customize dynamic, powerful OpenCart templates to make your website stand out from the crowd

• Fully customizable administration theme for OpenCart

You can purchase the book here:

https://www.packtpub.com/opencart-14-template-design-cookbook/book

This book goes quite indepth on customising opencart, of couse you need some basic PHP and HTML skills.