Look into Tor at https://www.torproject.org/ and follow the download links to
Linux, and specifically to Ubuntu. You are advised not to use the repository
universe for Tor packages which require you to edit as root the
/etc/apt/sources.list file to incorporate the repository at the Tor project -
see https://www.torproject.org/docs/debian.html.en for that information.
Otherwise, see: https://www.torproject.org/docs/tor-doc-unix.html.en , and read
the Tor documentation at https://www.torproject.org/documentation.html.en