Hello,
Actually I’m glad you posted what commands you did; it gives us more information to narrow down your problem.
You’re not the only one that has this problem and probably not the last.
As for certs go, it’s a trial an error. I know everyone’s environment is different and it took a while till I was able to create certs and use them in Graylog. It was a long learning curve for myself and takes time to do it right.
I agree it is confusing, In my opinion I would start off by using this link, specially as a guide of what you need to do. Use the other links like this link as reference. In this post there are several links on how to create certificates. Some may or may not work for you.
hope this helps