First time users
If you are unfamiliar with ROS and intend to use the ROS API, it is highly recommended that you read the ROS Tutorials.
If you are unfamiliar with the terminal on Linux, you should look here.
Shadow software is deployed using Docker. Docker is a container framework where each container image is a lightweight, stand-alone, executable package that includes everything needed to run it. It is similar to a virtual machine but with much less overhead.