I don't want to use auto generation task form in human task.I want to integrate custom adf application with bpm project[call adf screen in to our bmp11g application]. can any one suggest me on this argent.I new for bpm.
This should give an idea - http://andrejusb.blogspot.in/2012/07/lightweight-adf-task-flow-for-bpm-human.html
Also what you can do is generate the taskForm and in the taskDetails1.jspx which is autogenerated you can plug in a taskflow which you have created dropping it as a region.
http://andrejusb.blogspot.in/2010/10/initializing-oracle-bpm-11g-process.html (This might help to understand how to transfer payload)
In addition to what Sudipto already mentioned, here is one post that can give you internal architecture and how exactly all this ADF TaskForms fit into any SOA/BPM applications. Below post has references to some more posts worth reading. Some of them are pretty long but kind of more detailed :) and hopefully should give you some perspective for your requirement.