Reply to Help with controller and headphones

I have a BCD3000. Im new to this so I don't know much about setting up the controller, so I connect my speakers and my headphones and it all sounds perfect but when I want to play a song through the speakers and cue another through the headphones I don't know how to do it, I tried everything in the User Manual it comes with but It doesn't work, I don't understand what should I do. any help?