Docker is a developer* tool, not really something you should be using without some technical knowledge, or at least some experience in the terminal. It’s purely a terminal application, so you just type “docker” in the terminal to use it. You can also type “man docker” to view the manual (which shows arguments and command you can use) but again, that won’t help much without some prior knowledge.
The things you’re trying to use look like self-hosted web servers, which is a lot to set up for someone who’s new to the terminal. I won’t stop you if you want, but be warned. I’d recommend using something simpler like cozy, which you should be able to find and download in the software store.
*Edit: it’s not only a developer tool, it’s used for deployment as well. I lumped the two together. It’s still a tool made for people with more familiarity using the terminal though.