How to add link path?

I’m very new to CMS systems and WP.
I’d like to at a link path, or what it’s called, to my site, like this forum uses at the top of the page.
I’m sure it’s not called a link path, since that doesn’t give any helpful result when searching, but I don’t know what else to call it.

How can I do this, please?
I’m running the theme Hemingway, if that’s relevant.