Forget what you may have heard how hard it is to use the command line interface
If you can text, you can type, and if you can type you can operate the command line interface (CLI) in a terminal app. It's that simple.
To start, focus on the essentials.
There are hundreds of commands and more arriving all the time. The driving principal is that each should do one thing and do it well. (While this is true for the core commands, there's no guarantees as to the add-ons.)