ok ... well you understand ps2 kb and mouse.
That is, you have two computers, they have wires from their kb/mouse area that go to the switch. In addition you have your wires from the mouse and kb that go to your kvm. So, when you hit the switch you are controlling the other computer. Likewise when you have your monitors plugged into the switch, and you have monitor cables from the computers to the kvm switch you can switch back and forth between video inputs. This concept also applies to sound. you plug the output wires from your sound card to the KVM for both computers, then when you are switched to one of the computers you will be recieving sound from that particular one.