In this video series Karen Stevenson, Michelle Lauer and Joe Shindelar take a look at the Organic Groups module for Drupal 7. The series starts from the basics and goes through the various requried modules used to build a site with Organic Groups and then gets in depth with creating groups, adding content to groups, and dealing with group membership.
In addition to the basics of creating groups the series also takes a look at the various settings related to both access control and permissions and how you can combine them to create private and public groups. How to use the OG Extras module to display more information on the main group page and then how to use the Panels module to display group content and other advanced Fields and Views configuration related to OG.
This video assumes that you understand the basics of content, fields, and Views in Drupal. If you need a refresher on these topics here are some other tutorial series to review:
Note: There have been significant changes to Organic Groups since this lesson was made. We use the 7.x-2.x-dev version from May 2012, or the equivalent of 7.x-2.0-alpha3, in our lessons. Though we would like to revisit this series to update it, we have no current schedule to complete that. The best place to figure out what has changed and why, would be the Organic Groups issue queue on Drupal.org (http://drupal.org/project/issues/search/og).