Use a car power adapter, contains all those goodies for you.https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=car+cell+phone+chargerConnect to the USB port on your Arduino.
The board can operate on an external supply from 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may become unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.
First, how a zener actually works and how it is wired up,