Let me see if I understand this correctly. You do not want to write portlets and deploy them to JBoss Portal. Instead, what you want to do is embed JBoss Portal (or a portlet container) within a web application that you have already written (or are attempting to write). Or are you perhaps attempting to write a portlet container and thinking that embedding JBoss Portal would be a simple way of doing this?
If you want to write portlets, then the documentation should provide all the help you need to create an deploy a portlet.
If you want to embed (or write your own) the portlet container, you should get the portlet spec from the JCP web site. Other than that you are on your own.