sending data to the processor using the PC USB port

I want to write a C++ application to send data through the USB port to the NIOS processor on the DE2-Board. I have no idea how I should develop the software paltform to use the USB port. I do not intend to use the NIOS II IDE software to use the USB port. I would like to write a stand-alone C++ program. Is there any available libraries or classes to do so? plz help me :(