These commands need to be run using sudo.

Export the username you want to add:
{{{
export NEWTRACUSER=nickname
}}}
To add a user:
{{{
trac-admin /web/tech.transitionnetwork.org/trac permission add $NEWTRACUSER admin
}}}
To set their password:
{{{
htpasswd /web/tech.transitionnetwork.org/.htpasswd $NEWTRACUSER 
}}}
You then need to login as the new user to set their email address for email notifications to work.