Complete beginner..how do i install this?

Hey plantitious, not sure if you found it now, but if not, you need to be hosting your site. What I did was upload the ZIP file via my File Manager and extracted it in there. Once this was done and the plugin was visible on my WP Admin Dashboard, I activated it. Then back in the dashboard, went to the ‘settings’ tab and then ‘insert headers and footers’. This is where I pasted the script. Hope it helps!