There is no address like you posted!!! And even if there was, you shouldn’t touch there anything.
Read again my post: the sidebar.php of your active theme.
Which means, you either edit that in the online Theme Editor (admin > Presentation > Theme Editor) – but that’s a very unhealthy thing for beginners…
or you edit the file on your computer, after making a backup copy in case you screww it up, and you upload/ftp the edited version to your server.