You can refer to the following link to get the appserver documentation.
http://developers.sun.com/prodtech/appserver/reference/docs/index.html
Alternatively you can use netbeans IDE to develop J2EE applications. It is very simple to write, package and deploy J2EE applications using netbeans.
You can download netbeans from-
http://www.netbeans.org/downloads/index.html or from
http://java.sun.com/j2ee/1.4/download.html