Did you try that command as root? The hash (#) isn't part of the command it is to signify that you should run the following command as the root user, according to the docs `pg_ctl start` is how to start the server, or depending on your distribution you could try /etc/init.d/postgresql start
Read this install guide
http://www.oryx.com/ams/postgresql.html and see what you have missed out.
If your still stuck please tell me what distribution you are using and how you installed postgresql by the distributions's package manager or by source? As I have already said I haven't used postgresql, when I looked at the different database servers MySQL fit the bill better so I went with that, but I'll help you as much as I can