Re: tutorial problem solution requires that problem is already fixed

Elsewhere you should have already learned that PostgreSQL solves the bootstrap problem by creating an initial superuser and database during the running of the "initdb" command.  You connect as that user to that database to create your second user (and possibly database).  Both are named "postgres" by default.  Though the documentation mostly concerns itself with compiled-from-source installations; whatever package you installed usually with provide additional information as to how to work with the system immediately after installation.

David J.