How do I copy/paste an image from my computer drive e.g.
C://Downloads/filename.ext to my essay?

I tried twice and I either get ...crickets or just "filename.ext".

I want to embed the image, not the link.

The instructions at the bottom of the page are less than useless.

Images with a data-picture-mapping attribute will be responsive, with a file size appropriate for the browser width.

?? ?

Many thanks
td