Thanks for your question, @DM4C.
It's a little counter-intuitive, but you'll need to add a second site first so that the site-switcher shows up and provides the copy option. Click on the menu on the top right and then click the link to add a new site. Follow the steps to do that until you are in the website editor, then exit back to the dashboard. You'll then see a grey sites dropdown on the top left. Click on that, then click the "..." for your original site and you'll see a copy option.
