Thanks my friends WPScientist and fireform for your clarification.
You'll need to write the code by yourself.
Look into HTML, CSS, JS (basics is enough) and jQuery. That's pretty much all you need to code a HTML template.
When you get some basic knowledge in those, buy a few HTML templates and look at the code, that's always a great source of information.
Learn a bit about code structure and organization as well.
It's all pretty much simple, a few months of learning to be able to make an HTML template, but you'll never "learn" you'll always be "learning", things change at a quite fast pace in web development.