...keyboard?

The KVM switch you have has only ps/2 inputs. The keyboard is probably usb. So you'll have to buy an adapter from usb to ps/2. they are very cheap. Although the solution works theoretically in practice things change. Those adapters aren't a solution. So if you really have to work with the kvm buy a ps/2 keyboard.If you mean how to switch between computers then hit scroll lock two times and then the key (1, 2, 3 etc) corresponding to the computer you want to log onto.