Books, periodicals, internet searches, practicing everything at home on a personal equipment until you've got it all mastered. If one can't learn that way, take courses. The way the rest of us did it. Once you've got that, you have the ability to learn anything new coming... and can hit internet forums with well formed questions, complete with context. Staying on nano/pico, there is just no excuse if you've already been heavily using linux for 3 years or more. It's an editor for those who are still in the beginning of the SELF learning phase. It should never be included in any distro's default install except for school classroom centered distros. Just because something is easy to use doesn't mean it's installed as a standard everywhere. Folks learning this as their craft need to learn how to sit in front of any Linux or Unix and use standard tools to achieve what they need to do. That means learn your Vi. Learn your Posix shells like Ksh, Bash, Zsh, Dash, not the nano of shells, fish! Learn your Python, your Perl. Learn your SysV 'isms in addition to your SystemD. Learn your csh (tcsh will do). Learn your terminal control codes. Learn your SysRq funtions. Learn your tmux, your gnu screen. Learn with and keep handy your books for awk, sed, patterns, perl. Learn your mkfs', the different filesystems and their benefits, their options and tools, how to resize. Learn your MD raid. Learn your LVM. Learn various encrypt at rest options. Learn containers. Study and remember the differences between gnu, bsd, and sysv tools like tar, cpio, find, and even ps. Books books books! Practice practice practice! Study study study!

And when you got that done, look up and see what you've missed while you were doing all that, and start in on all that new stuff. Wash, Rinse, Repeat. Never stop reading, studying, practicing, learning.

That's how. Oh, and delete nano!!!!