Help regarding DFU.

Hi All,
Can anyone provide me any links that help in writing DFU class HID
driver.Any sample code such as framework.I dont know were to start.I
need to upgrade the firmware of my usb device when required.
I am new to windows driver.I jus know the skeleton of the driver,the
basic routines such driver entry,Add device routine,few dispatch
functionalities,not all etc.I jus know few terms in the driver and how
it works.
My requirement is to write a DFU class HID driver for a usb device.
My questions are:
How will I signal my usb device to re-enumerate.Is there any IRP_MN_XXX
to reset the device.If so from where will I send this IRP to
re-enumerate the device.If it is an IRP_MN_XXX definitely it should be
handled in dispatchpnp( ).what all this I need to take care if that
particular IRP is send.
Basically I am confused.where to start.
Could anyone help me in providing a skeleton code for a DFU class HID
driver
Thanks in advance.
It would be great if you help.
zyx