Just finished reading "The Docker Book"

An excellent quick little book. It's a kindle only and with estimated 259 pages... well... it feels more like 70 (in the good sense).

This is essentially an in-depth tutorial on all basic use cases of Docker. Since for Docker Nginx is the same as MySQL or Jenkins, in this book you will find stacks delivering complex functionalities using lots of heterogeneous components. It is probably one of the few times you will install Java on Ubuntu and tons of software on top of it without even realizing.

Reserve a few hours to go through some of the examples - they are all runnable - and you will gain some good confidence on using Docker.

P.S. If you're using boot2docker, sudo might not be necessary.