Total Newbie: Trouble installing postgresSQL on OS X Snow Leopard

Hi all, I am trying to get set up with a database in PostgresSQL and
eventually postGIS, so followed the install instructions on Kyng Chaos' web
site:
http://www.kyngchaos.com/software:postgres

(I installed all of the items in the list with the exception of "PostgreSQL
Client-only 9.1.2-1"). Then I entered the Terminal, and went through the
following, with little luck. Can anyone help or point me in the right
direction to get a new database set up?

>> My suspicion is that the problem lies in the line (below) where it says:

*initdb: could not access directory "/usr/local/pgsql-9.1/data": Permission
denied*

Many thanks!
Kevin

>> My system: OS X 10.6.8 Snow Leopard
>> First, I tried to create a new data base called "db1":

kevin-gouldings-imac:~ kevingoulding$ /usr/local/pgsql/bin/psql -U postgres
-d db1 -f /usr/local/pgsql/share/contrib/postgis-1.5/postgis.sql
psql: FATAL: database "db1" does not exist

>> Then I wasn't sure if postgresSQL had in fact been installed / launched
correctly. So I entered this code and my password:

kevin-gouldings-imac:~ kevingoulding$ sudo launchctl load
/Library/LaunchDaemons/org.postgresql.postgres.plist

WARNING: Improper use of the sudo command could lead to data loss
or the deletion of important system files. Please double-check your
typing when using sudo. Type "man sudo" for more information.

To proceed, enter your password, or type Ctrl-C to abort.

Password:
org.postgresql.postgres: Already loaded

>> It appeared that in fact it had already been loaded. Then I read
further down on Kyng Chaos' page, where he says to try the following
command:

kevin-gouldings-imac:~ kevingoulding$ /usr/local/pgsql-9.1/bin/initdb -U
postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
The files belonging to this database system will be owned by user
"kevingoulding".
This user must also own the server process.

The database cluster will be initialized with locale en_US.
The default text search configuration will be set to "english".

initdb: could not access directory "/usr/local/pgsql-9.1/data": Permission
denied

>> It appears that I do not have access to the directory, or haven't set up
the permissions, roles, etc. So I tried a bunch of commands, attempting to
create a new role "kevingoulding":

kevin-gouldings-imac:~ kevingoulding$ /usr/local/pgsql/bin/createdb mydb
createdb: could not connect to database postgres: FATAL: role
"kevingoulding" does not exist
kevin-gouldings-imac:~ kevingoulding$ CREATE ROLE kevingoulding
-bash: CREATE: command not found
kevin-gouldings-imac:~ kevingoulding$ createuser kevingoulding
-bash: createuser: command not found
kevin-gouldings-imac:~ kevingoulding$ $ postmaster -D /usr/local/pgsql/data
-bash: $: command not found
kevin-gouldings-imac:~ kevingoulding$ postmaster -D /usr/local/pgsql/data
-bash: postmaster: command not found

>> Then I found this code to see if postgresSQL was running. This might be
helpful, but I do not know what it means.

kevin-gouldings-imac:~ kevingoulding$ ps auxwww | grep postgres
kevingoulding 14625 0.3 0.0 2425524 172 s000 U+ 10:08PM 0:00.00
grep postgres
postgres 12360 0.0 0.0 2454996 248 ?? Ss Tue09AM 0:02.08
postgres: stats collector process
postgres 12359 0.0 0.0 2458912 724 ?? Ss Tue09AM 0:02.27
postgres: autovacuum launcher process
postgres 12358 0.0 0.0 2458780 240 ?? Ss Tue09AM 0:08.90
postgres: wal writer process
postgres 12357 0.0 0.0 2458780 304 ?? Ss Tue09AM 0:12.64
postgres: writer process
postgres 12355 0.0 0.0 2454996 216 ?? Ss Tue09AM 0:02.72
postgres: logger process
postgres 12352 0.0 0.0 2458256 1008 ?? Ss Tue09AM 0:00.58
/usr/local/pgsql/bin/postmaster -D /usr/local/pgsql/data