Each page is an .html file with the corresponding letter in front. (e.g. c.html) The home page is index.html. The HTML includes comments that signpost the different sections!
The "elements.html" files contain code for the various elements you can use in a page.
Some of the other .html files, like "about.html" are remnants of the original Bootstrap Template. They can be deleted at this point.
All assets are in the "img" folder. "/img/examples" contains the additional examples using a specific naming convention.
All the H5P content is hosted on WI+RE's CCLE site.