The Odoo framework provides a lot of power, but also comes with a fairly steep learning curve. While Chapter 16, Discovering Customer Odoo Modules, will help get you started, if you are serious about developing for Odoo, you will find the resources listed here in valuable in your pursuit.
Wouldn't it be great if you could try out a variety of Odoo builds and installations quickly and easily, without going through all the time and complexity of an Odoo installation? Well, fortunately, the Odoo Runbot provides you with many different Odoo branches that you can connect to and actually review the build for yourself.
This resource divides the installations by version, build, and age of the version. Even better, you can get immediate access to the branches right on GitHub, which is available at http://runbot.Odoo.com/.