could not connect to server: [then mess]

It's my first time using postgresql, and I might as well tell you my
first impressions.  I am reading
/usr/share/doc/postgresql/html/tutorial-createdb.html
and try
$ createdb mydb 2>&1|cat -v
  createdb: could not connect to database template1: could not connect
  to server: 8D+@M-HY&@^S
So disturbing to see the non ASCII stuff emitted.
[Version: 7.4.8. It turns out that the server was not even installed.
Anyway, bad message trailer.]

OK, so after poking around and getting to
/usr/share/doc/postgresql/html/installation.html#INSTALL-SHORT
It says
   su - postgres
   ...
   The long version is the rest of this chapter.
But in fact su... are not in the rest of the chapter.