Step 1: It begins with a Pigtail
On the picture you can see the wires- ground wire (in black shrink tubing), red/ black and green/white. Red is positive (+),black is negative (-). Green and white- data wires, for some devices they will need to be soldered together, in order to switch the device in charging mode. Read more about USB standards on the web. All parts are listed on Schematic page.