Connect USB cable to GPIO pins on an Arduino Uno Electronics Newbie!!

I want to connect a USB cable to my Uno's GPIO pins (and then connect it to a USB port on my computer). I have chopped off a USB cable from a keyboard, I read this and I'm hoping that the wires will be in the correct order (the keyboard was made by Dell). I'm a little confused about which wires go where.
The reason you are confused about which wires go where is simply because the Uno has no connection on it for a USB cable's wires.

You cannot directly interface an Uno to a USB port without extra hardware.  What hardware you require depends on exactly what it is you think you are trying to achieve.

(There have been some attempts to create a USB device interface purely in software, but personally I wouldn't touch it with a barge pole - the GPIO of the Arduino is not electrically compatible with USB.)