Prerequisities
This is a docker image, so you need to have docker installed.
Getting docker installed, is normally pretty easy, most of the time I just do:
curl -sSL https://get.docker.com | sudo sh
On my linux systems (including the Pi) and a short while later, docker is running.
Docker pull
This image is available in my registry, all you need to do is pull it:
docker pull registry.leenooks.net/bbs/fidohub:latest-[ARCH]
Change ARCH to either x86_64 for Intel or armv7l for Raspberry Pi.
Now you are ready to setup