Before you install a driver: install RethinkDB first.
Looking for another language? See the complete list of client drivers for RethinkDB.
Install the driver with gem:
sudo gem install rethinkdb
You can use the drivers from Ruby like this:
$ irb
require 'rethinkdb'
include RethinkDB::Shortcuts
r.connect(host: 'localhost', port: 28015).repl
r.db('test').table_create('tv_shows').run
r.table('tv_shows').insert('name' => 'Star Trek TNG').run
Move on to the ten-minute guide and learn how to use RethinkDB.