new to Drupal--using organic gropus in my site

Hi,
I am a newbie for Drupal and I should construct a site which contains
groups in it. Below is the installation environment;
--Red Hat Enterprise Linux 5
--Apache 1.3.41
--PHP 5.2.7
--PostgreSQL 8.3.5
--Drupal 6.9.

below should be the features of the site;
there will be groups that will be created by administrator and admin will
assign the group owner(basically the one who requested to construct that
group.)
every group should have a home page.
only the group members should see and create group content
let's say there are two groups created; finance and marketing
user financemember is the member of finance group only, financemember
should only see the finance group content not marketing group content.
Financemember should be able to create poll, event, discussion, forum.
there should be a document repository that members can download and upload
documents within registered group.

which modules should I use in order to construct that site and how to
configure them.
The most important thing is how to configure group based access namely
only member of the group display and create group content and how to
construct group home page.

Thank you for your help,
Reydan