I have found a nice Jboss 7.1 and EJB 3 Tutorial/Example under

http://theopentutorials.com/examples/java-ee/ejb3/how-to-create-a-simple-ejb3-project-in-eclipse-jboss-7-1/

I have created a diagram to understand the example.

Rar-archive from my workspace for that example is attached.

Have fun.