Pi4 fresh install - how to do docker for complete media downloader?

Duplicated from Reddit (any responses from there will be brought across to here as well.)

I've run my Pi4 as a self-contained usenet downloader and media centre using Thoradia until now. As that's no longer supported I've taken the plunge into what I think is the right way forward - Docker. But it's not as simple as I hoped (I can find my way around a computer well enough, but I'm always encountering new things I'm far from literate in.)

I've installed Docker and come to a halt. I had hoped the linuxserver.io repo would be my way in with SAB/Bazarr/Sonarr/Radarr, but most of the 'fleet' isn't listed. Then I thought DockStarter was a good route to follow, but it's baffled me too.

How do I access the add-ons I want in order to then configure them? Is there a whole Docker layer I'll need to wade through before I even get to Servarr config? (I've seen the Servarr/Docker wiki but it isn't helping me advance right now..) Any hand-holding/install guides/YouTube or shoving in the right direction is greatly appreciated.

Cheers

Quote from elonesna

My docker image information sources are (1) hub.docker.com (2) github (3) linuxserver and others. Start here. I recently installed 'linuxserver/jackett' and 'linuxserver/radarr' from scratch, and it's not difficult when configuring the service from the web page itself.

So here's what I found for myself (with a query at the end).

Using PuTTY to connect to the Pi4 over SSH I was able to look at docker and know it was there just by typing docker at the command prompt. Then using command docker search sabnzbd I could reveal a whole load of places I could download a SABnzbd docker image from. Knowing that the linuxserver.io fleet source was a good one (at least according to Servarr for Radarr/Sonarr/etc) I used the command docker pull linuxserver/sabnzbd. Once I'd got that I ran it using docker run linuxserver/sabnzbd.

My understanding is that this is an instance that runs only for the duration of the command issued (so if I inspected a file it would create the container, show me the file and then kill itself off. But the container continues to exist. Is this correct? Is this why I need to prune redundant containers before they get out of control?

While SABnzbd was running in PuTTY I could see it was opening a port (amongst other things), but I couldn't open a webpage to the IP:port. Is this to do with the port being created for the container, but the container port then needing to be mapped to the Pi ports? Do I now need to run the container with startup options, or something, to make the port mapping happen and reveal it over the network?