Believe it or not, but some people who use Gnus haven’t really used
Emacs much before they embarked on their journey on the Gnus Love Boat.
If you are one of those unfortunates to whom “C-M-a”, “kill the
region”, and “set gnus-flargblossen to an alist where the key
is a regexp that is used for matching on the group name” are magical
phrases with little or no meaning, then this appendix is for you. If
you are already familiar with Emacs, just ignore this and go fondle your
cat instead.