What is Tor?
Tor Project is a non-profit that develops the open source Tor protocols and software. Their website has a wealth of information about everything related to Tor:
Electronic Frontier Foundation (EFF)
The EFF is an advocacy organization which partners with Tor Project, and has created some helpful resources on Tor and how the encryption process works:
Written by the Tor Project, this manual is a comprehensive overview of installing, using, and maintaining Tor Browser.
Tor Project has also released a list of warnings to avoid activities that may compromise Tor Browser anonymity.
Tor Browser uses this plugin to help encrypt previously unsecured connections with target websites.
It is safest to download Tor Browser directly from Tor Project’s website, to avoid accidentally downloading a false or malicious copy.
Resources for Running Tor Exit Nodes in Libraries
This package by the Library Freedom Project can help your library advocate for and set up a Tor relay to support the Tor network.
Tor Client for Unix, Linux, and BSD
You will need a Tor client installed before you can run a relay. Running it on Ubuntu or Debian is preferred.