PS/2 to USB keyboard/mouse doesn't work.

Hello. I've recently bought a PS/2 to USB adapter.
But it doesn't work.
http://ecx.images-amazon.com/images/...L._SL1500_.jpg
I've been searching on internet and i found that i need something else.
The questions that i want to ask:

[s]Why this cheap piece of garbage doesn't work?[/s] - Solved.
[s]How do i manage to get it to work (Windows 8.1/Windows 7/ Windows XP) (1 PC, 1 laptop and another PC)[/s] - Solved.
That piece of garbage ..... what it used for? (You insert the PS/2 to the converter and then the USB end port to the computer)

Please help me!