It does help. It tells you exactly which pins on the USB connector to connect to which pins on the Xbox connector. All you have to do is a quick continuity check to work out which colour wire connects to which pin on each of the two connectors.
And your assumption is wrong - you don't connect it to a PC, you use the battery to provide power and the bulb to confirm continuity.
It doesn't matter how many questions you ask, the fact is that there is no mandatory standard for wire colours in a USB cable. You're the only person who has access to that particular USB cable, you have to work out the relationship between pin numbers and wire colours yourself.