I just love it when I run into a grumpy geezer that is older than I am.
I have to links that I think you may find useful. The first I think is the best.
http://www.tuxfiles.org/linuxhelp/cli.html
http://www.bit-tech.net/hardware/200...linux_cli_101/
Nothing written on this subject is written strictly in English. It is all mixed with Geek, a language that is hard to become fluent in.
I suggest that you pick one area of computer management that you are particularly interested in and concintrate on learning and using CLI commands for that. This will give you a start. When you start getting to know and understand some of those commands then would be the time to learn more.
What I am getting pretty good at is commands having to do with package management. Not expert by any means but I am getting to the point that I can handle that pretty well.
I use a text editor, usually gedit, to keep commands and a personal explaination for those commands in files relating to different things. The largest is package management for me.
This is, at least for me, a good thing to do because I can at least understand the explaination.
One thing that Ubuntu does not do that all other distros that I know of do is to give you a root password and a root terminal.
You can, however, avoid excessive use of sudo by opening a terminal and;
This will require your password and then open a root prompt for you (user prompt=$, root prompt=#). This will last untill you return to the user prompt which you can do at any time by hitting Ctrl+D. Ctrl+D is also the best way to close your terminal as it will not fill the terminal history with "exit" commands.