There's an IBM i hobbyist discord[1] full of friendly people who will be happy to help you out with learning or acquiring your own iron, or you can use any of a number of public-access systems. The main public access system is pub400[2], but there are at least three that are run by people in the discord. I run one of them, albeit with the worst uptime of the bunch; PM for details. And finally, you can find all of the docs for the system on IBM's site[3], though they can take some getting used to.

[1] https://discord.gg/MzYzSvzN, or #ibmi on freenode [2] https://pub400.com/ [3] https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_73/rza...