Create a new folder called intermediatesite alongside the one called beginnersite (not in it).
In your beginnersite folder copy the templates (at least HTML and CSS but also the PHP template if you have one). Paste them into the new intermediatesite folder. If you do not have these templates create them now. They are just files with the basics in (for HTML include head, a meta tag for character set UTF-8, title, link to style sheet, embedded style element, script element, body element and an h1 element)
You already know about what is in the template and is important for any Web page (the head element, body element, indenting and file naming). If not go back and do the Beginner tutorial! Here is a bit more detail to tweak and improve your pages.