Start by installing and running the tk4 MVS distribution. There are lots of youtube videos about it. Watch everything you can find in video about mainframes. Re

Start by installing and running the tk4 MVS distribution. There are lots of youtube videos about it. Watch everything you can find in video about mainframes. Read a lot of IBM docs. Start by the ABC's of Z/OS Programming or some older equivalent, since you won't be running the newest system on the emulators anyway.