These tutorials cover the basics of creating messaging applications using RabbitMQ and Java. You need to have the RabbitMQ server installed and running to go through the tutorials.
Code samples are available on github for Java and C#.
The simplest thing that does something

Distributing tasks among workers

Sending messages to many consumers at once

Receiving messages selectively

Receiving messages based on a pattern

Remote procedure call implementation

Once you have been through the tutorials (or if you want to skip ahead), you may wish to read an Introduction to AMQP Concepts and browse our AMQP Quick Reference Guide.