I'm also a quite unexperienced computer user (I do have some experience, but not what is need to be called advanced).
As an addendum, if you ever need to remember what has just done, most (but not all) free software nowadays have long but friendlier options. The "-h" short option of GNU Df is equal to the "--human-readable" long option. If you have the "bash-completion" package installed (someone please correct me if I'm wrong about the package name, or if it's not needed at all), you just have to write the option until "--hu" and then press TAB once to get "--human-readable" written for you. "bash-completion" doesn't work for every command, but it's very helpful. Also, if you want to, there's alway GNU Info (the "info" command) which you can use like this: info df To see the documentation for the "df" command (GNU Df). Once done, press Q do quit GNU Info gracefully/gently.
