Help linking CDJ's 900 nexus

I recentely got two cdjs 900 nexus and a djm 850, I need some help connecting the cables when they arrive... I think I need to plug the L and R rca's from the cdjs to the djm right? But then how do I link them? I don't want to use laptops or any else, only USB sticks, but I don't know how i'm going to link them since I never did such a thing, what do I need and how do I connect them?