docker hub

https://hub.docker.com/
https://docs.docker.com/userguide/dockerrepos/
https://docs.docker.com/examples/running_ssh_service/
https://docs.docker.com/engine/reference/builder/
https://philipzheng.gitbooks.io/docker_practice/content/image/create.html
https://docs.docker.com/engine/userguide/containers/dockerimages/

(put Dockerfile in current dir)

$ docker build -t AAA/bbb . (-t is optional, it will save to AAA/bbb if succeed)
$ docker login
$ docker push AAA/bbb

[Note] you can also exec into docker and modify it, then commit(docker commit) it as new image (can look at the history if still exist...)