There are a few things you need in order to make a car usb charger. The first is an usb port on your device, the second is a usb cable, and the last is the charger itself. The usb port on your device will need to be compatible with the usb cable that you will be using to charge your device. If your device does not have an usb port, then you can purchase one from a store or online. Once you have the usb port and cable, it is time to begin charging your device! To charge your device, plug the usb cable into the USB port on your device and plug the other end of the cable into an outlet. Your devices should now be charging!