You will need a 5V power supply to power your setup. You can use an old cell phone charger as all cell phones with USB charging are 5V rated.

If you prefer to use battery power, a neat trick is to power your setup with a USB power bank like the ones used to charge phones. USB has a voltage rating of 5V and an amperage of more than 1V, which is more than enough to power our setup. When the battery goes down, you can simply charge your power bank again and continue using it. Adafruit sells a small power bank, but you can find one of these at any neighborhood cell phone stores (https://www.adafruit.com/product/1959):

In both of the previous cases, you will also need a USB cable to connect to the power bank or cell phone charger. You will need to strip the USB cable at the other end and find the VCC and GND wires. You can do this using a multimeter. In general, if you see a red wire, it's usually the 5V VCC and the black wire is usually the GND.