The official documentation is at: http://docs.alfresco.com
This page serves as a guide to the Alfresco Wiki and external resources related to Content Modeling.
Wiki Articles
For an overview article describing content modeling, including an example tutorial, you should start with Data Dictionary Guide. After that, continue on to Displaying Custom Metadata to learn how to expose content model properties in the Alfresco Web Client. After that, you can move on to other articles; here are the articles tagged as being related to
Content Modeling.
External Resources
Additionally, Jeff Potts wrote a great series of tutorials explaining various aspects of content modeling. These are recommended as a great supplementary resource. They can be found at Jeff's Site - http://ecmarchitect.com.
For offline reading, Jeff extended this series into a whole book, The Guide (well actually 'The Alfresco Developer Guide', but that page does exist in the wiki already.
Training
Additionally, Alfresco and its Training Partnes (depending on geography) offer an instructor-led Content Modeling Course with many hands-on labs. If you are interested in classroom instruction, please contact Alfresco at training@alfresco.com.
Getting Started
Content Modeling
