Basic instructions are included on the case. See this PDF for additional information on how to set up the hotspot, and lending rules.
Charging the Hotspot:
When the battery indicator flashes red, the hotspot will need to be charged. Connect the USB cable between the hotspot and the adapter, and plug it into an electrical socket to start charging. You can also charge the device by connecting it to a PC with the USB cable. When the hotspot is powered off, it will take about 3 - 4 hours to fully charge.