By no means is this chapter a tutorial on using PowerShell. But if you want a better understanding of the examples or learn more about PowerShell, I can recommend you reading the book Mastering Windows PowerShell Scripts (ISBN 9781787126305). I suggest that you start with second chapter Working with PowerShell and continue until at least fourth chapter Working with Objects in PowerShell.
You can find more then enough online documentation about using SSH. A very good start is the wikibook: https://en.wikibooks.org/wiki/OpenSSH.
There is also a very old book, SSH, The Secure Shell: The Definitive Guide (ISBN 978-0596008956), which is still a valid source of information, especially for system engineers.
