Streaming Replication Configuration

I'm attempting today to get streaming replication from the Wiki
configured on my two 9.1.2 servers:
http://wiki.postgresql.org/wiki/Streaming_Replication

I'm on step #6

6. Make a base backup by copying the primary server's data directory
to the standby server.

$ psql -c "SELECT pg_start_backup('label', true)"
$ rsync -a ${PGDATA}/ standby:/srv/pgsql/standby/ --exclude postmaster.pid
$ psql -c "SELECT pg_stop_backup()"

When I attempt the 1st command listed on my primary (master) server, I
get this error:

carlos(at)db1:~$ psql -c "SELECT pg_start_backup('label', true)"
psql: FATAL: database "carlos" does not exist

Now I'm showing they want me to use the -c switch to connect but no
database is defined so is it implied that I need to add 'postgres'
maintenance database in there or something else?