Can anyone point me to any documents or URL to develop customized JSP for PPM? I have a set of JSP pages needed to be developed and integrate into PPM. So to users, it would be perceived as part of PPM.
Chapter 5 of the document called Customizing the Standard Interface describes what to do to modify JSPs and how these are assembled. If you want to create your own pages, you should look for a simple one in PPM with rather static content, then find the JSP in the file system, make a copy and modify that copy to include your custom content. Finally, to make these new JSPs available to your users, you could add custom entries in your menu. Chapter 3 of the same doc explains how to read and modify the menu.xml file.
Let's say you copy a not too complex existing JSP like /itg/web/knta/crt/RequestCreateList.jsp and start from there. Or you construct it more or less from scratch. It should include: <%@ page errorPage="../global/Error.jsp" %> ... your content goes here ...
above, these are relative URLs, depending on where you place your cutom JSPs you may need to adjust them.