How can I make new user in postgresql?

How can I make new user in postgresql?

How can I make postgres work with django in a virtualenv?
Errors :
New Roles are being created but I can't see them in pg_hba.conf
CMD: createdb -U postgres -T template_postgis fixmystreet
gives an error both inside virtualenv and on root:
Error : createdb: could not connect to database postgres: FATAL: Peer
authentication failed for user "postgres"
FYI: I am new to both django and postgres so I'm doing
https://github.com/visiblegovernment/django-fixmystreet/wiki/Installation
to get familiar with them. Any help is appreciated.