Start Docker

In which order, what exactly needs to be installed?

If i click on your link, i get to github. As i know i have first to install Docker.
But which Docker Version, as you said i’m not using the right one.

If i go here:

It says:
To get started with Plex Media Server in Docker start by installing Docker on your platform of choice - in other words, every Docker Version should work. So apt-get install docker should be fine, right?

After installing Docker, i need to create a working Configuration.
After Config just start the Docker by Docker start blabla and then run the Script again.
Am i right or did i miss something?