Regions and templates

{% include "radix:html" %} In SDC world, it means that go load the html.twig file from the Radix component list. I suggest you start by reading the documentation and watching the first part of the video tutorial

But in short, yes, you copy over the component to your subtheme and modify it there. For an easier process, I suggest using drupal-radix-cli

Marking this as closed. feel free to ask more questions if its unclear after going through the items above.

Yeah, this new world of components takes a little getting used to.

In your case, for adding some regions, you probably don't need to copy over the radix:html component to your mysubtheme:html .

For adding page regions, just copy over the radix:page-content and possibly radix:page components. Those components are where you can create some more regions. You would use mysubtheme:page-contents if you want regions with constrained width; you might use mysubtheme:page if you want additional full-width header or footer regions.

Thank you very much for the answers. I see that part of my question has to do with SDC World, but I didn't want to start changing too many twig files without knowing, without having some answers. I really like the look of Radix; I'll continue learning how to use it.