Most terminals start a shell as the first program, so you're not really learning "Terminal" so much as whatever program it starts first. Bash is a pretty common shell, so you might want to search for things like "Bash examples" to get a feel for it.
If that's too simple, or you blast past that, then reading bash's manual might give you some more ideas. The man command is your friend. The manuals are not necessarily quite so friendly, but they're aimed at someone who's already somewhat competent.
If Bash isn't what you have where you are, substitute its name instead. Zsh and Fish are pretty popular. There are others, but I don't think any mainstream Linux uses them by default.
To check what shell you're using try an echo $0 or echo $SHELL.
Finally, a bit of advice: Don't go running commands you see on the Internet unless you're sure what they're going to do is something you have no problem with. And be careful with copy/pasting from web pages you don't know or trust - I can't vouch for the examples in the link I gave earlier, for example. It's possible to make things look like a completely innocent command but when pasted does something else entirely.