Port Replicator

I am setting up a port replicator for my uncle, which I have NEVER used before. He wants it to link his dell dimension 3000 desktop to his dell latitude d810 laptop.  I figured out how to dock the laptop, but I don't understand how to connect the two.  Where do the cables come from? I just don't understand and he's not around to help.  Any advice would be greatly appreciated.