Just as a proof-of-concept, if you locate the Quark theme file at user/themes/quark/templates/partials/blog/date.html.twig and view the file you should see this:
Nothing fancy of course, but this should be a good start for you.
A more elegant approach would be to create a new author.html.twig template file in that same folder, and then include that as a partial here:
Just as a heads-up, direct edits to theme files can be overwritten during theme updates, so it is a good idea to first create a child or inherited theme (which is best for smaller changes) - more info at https://learn.getgrav.org/15/themes/customization#theme-inheritance
Again, nothing fancy but should help point you to the right spot etc. You would likely also want to move that author.html.twig file to just user/themes/quark/templates/partials/
BTW, I am not a dev myself but once you are learning some of the basics of the Grav architecture it is pretty amazing what you can do with a bit of HTML/CSS/Twig knowledge.
I got it now, using the info you gave me was pretty much instant learning.
I created a new page type (Articles) based off default, using bits and pieces from blog.