This has been doing my head in all day – so hopefully it will save some of you the trouble. I’m on a CentOS box. First thing you want to do is check which version of postgres you have, with:
Here’s a quick reference on how to create a user, a database and grant the user all privileges to the database (on Mac OS X). If you haven’t yet installed PostgreSQL, look here: How to install PostgreSQL on Mac OS X
There are a number of ways to install Postgres on Mac, here’s three. While these instructions are for a clean install of Lion, they may work for Mountain Lion.