try sun's reference-implementation (j2eesdk).
it comes with a nice deployment-tool where you can create an ear/war via 'click-click'.
afterwards you can have a look to the layout into the result-ear with a real-men's ;) deployment tool like 'jar'.
thats how i started to learn about this.
You should also spend some time reading the various
J2EE specs from Sun. They outline all this fairly
well as well (in more detail than you want to know,