The absolute bare minimum you need to know on the command line
GUIs change, but the command line is eternal. Memorize these 5 commands and a long and happy life awaits.
$cd
change directory. This is how you move
around the file system.
$ls
List, or tell me what's in this directory. This has a
huge list of useful modifying flags, such as -l (long,
tell me the size, ownership, and permissions on each
thing in here too), or -a (all, as in, show me hidden
dotfiles as well)
$mv
Move, this is how you move something from here
to there. This is...