Hello!
If you have Glassfish server installed on your computer you can find good tutorial on
EJB at "..\glassfish3\glassfish\docs\javaee-tutorial\examples\ejb".
Again to find out how to use it and what is ejb refer to part IV and part V of javaee6 tutorial at
http://docs.oracle.com/javaee/6/tutorial/doc/javaeetutorial6.pdf
I am sure that any other server includes ejb examples as well! It is needed to look for them where you have server installed on your computer