Once pulled the image, execute:
$ docker create -t -i --name joern -p 7474:7474 m4mbr3/joern-image:v1 /bin/bash
to create the container from the image.
$ docker start joern
$ docker attach joern
to connect to the instance.
In / there is a script to start the neoj4 db in background. All the other important files are in /root/ including the folder of file with the modifications.