index.html, find all placeholders (eg @@FOO@@) and replace them with actual information (eg title, author, content)index.html, style.css, behaviour.jsindex.html:
    lang attribute of <html> accordingly<nav>, <main>, <aside>; decide whether you need one, two, or
the three of them, and enable/disable them (about this, read more below)@@FOO@@) and replace them with actual information (eg title, author, content)index.html.
Ditto about images and other resources.
Do not edit the resource files that are part of the template (eg style.css, behaviour.js).<main> should always be there, and hold the bulk or the important content of the page.
Even if that content is just a paragraph.
Do not remove it.
You can decide whether you need the other two elements.
As a general rule, most pages will benefit from a <nav> element to facilitate internal navigation.
<aside> may be handy if there is “extra” content that you want to be in a separate area.
Good examples of this are: contact details for a person, fixed links to resources of a working group, a quotation that complements or expands the content of the
page, a list of “related articles”…
If your page should look or behave differently on UAs that run JavaScript, know that the element <html> will always have one of these two classes, depending
on whether JS is running or not: no-js, js.
You can use that to tweak CSS rules.