IBM has published a very nice document about Docker on the mainframe.
PDF download as well as via Knowledge Center. You can read one of the best container/Docker introductions I've seen on the Internet, as well as a good coverage of basic concepts around containers and Docker in the context of Z.
1. Docker basics
2. Components in a Docker environment
3. Planning for Docker
4. Managing images
6. Avoiding common pitfalls
Here is the table of contents:
IBM Knowledge Center (which carries most of IBM's documentation) keeps all this searchable and always provides the most recent informatoin.