Getting started with Liferay.

There are a lot of info over the Internet related starting with Liferay.
Here I'll just summarize info that was helpfull for me.

1. To start working with liferay you shoul install it, here you can find quick installation guide.
2. To make life easier it is better to extend Liferay and develop new portlets under Liferay IDE, here you can find installation guide for it.
3. Development guide for version 6.0, pay attention to portal-ext.properties, ext-plugin, hooks, portlets and themes.
4. Liferay Wiki 
5. Introduction to Java portlet specification.

Paul