If you don’t know GNU Emacs, you can still read this document profitably. However, I recommend you learn Emacs, if only to learn to move around your computer screen. You can teach yourself how to use Emacs with the built-in tutorial. To use it, type C-h t. (This means you press and release the CTRL key and the h at the same time, and then press and release t.)
Also, I often refer to one of Emacs’s standard commands by listing the
keys which you press to invoke the command and then giving the name of
the command in parentheses, like this: M-C-\
(indent-region). What this means is that the
indent-region command is customarily invoked by typing
M-C-\. (You can, if you wish, change the keys that are typed to
invoke the command; this is called rebinding. See Keymaps.) The abbreviation M-C-\ means that you type your
META key, CTRL key and \ key all at the same time.
(On many modern keyboards the META key is labeled
ALT.)
Sometimes a combination like this is called a keychord, since it is
similar to the way you play a chord on a piano. If your keyboard does
not have a META key, the ESC key prefix is used in place
of it. In this case, M-C-\ means that you press and release your
ESC key and then type the CTRL key and the \ key at
the same time. But usually M-C-\ means press the CTRL key
along with the key that is labeled ALT and, at the same time,
press the \ key.
In addition to typing a lone keychord, you can prefix what you type with C-u, which is called the universal argument. The C-u keychord passes an argument to the subsequent command. Thus, to indent a region of plain text by 6 spaces, mark the region, and then type C-u 6 M-C-\. (If you do not specify a number, Emacs either passes the number 4 to the command or otherwise runs the command differently than it would otherwise.) See Numeric Arguments in The GNU Emacs Manual.
If you are reading this in Info using GNU Emacs, you can read through this whole document just by pressing the space bar, SPC. (To learn about Info, type C-h i and then select Info.)
A note on terminology: when I use the word Lisp alone, I often am referring to the various dialects of Lisp in general, but when I speak of Emacs Lisp, I am referring to GNU Emacs Lisp in particular.