I clicked through the linked page, and it's not clear to me how to actually add analytics to my site? The instructions in the repo direct me to launch a golang

I clicked through the linked page, and it's not clear to me how to actually add analytics to my site? The instructions in the repo direct me to launch a golang daemon for what appears to be the dashboard. It would be awesome to have a more cohesive example. Is this reading log files? Or using client-side JS? If the latter, do I have to have the Fathom server internet-facing so that the JS can report in?