You can also connect with the TTL serial input. This is the red/black/white cable. Power is provided by connecting the black wire to ground and the red wire to +5V. The white cable is the 5V TTL serial input. By default, the backpack is configured for 9600 baud, 8 bit, no parity, 1 stop bit. You can configure the baud rate if you need faster/slower TTL interface. When powered, the backpack will blink the baud rate onto the display for 100 milliseconds so if you're ever really confused, connect while watching the display. You can always connect with USB (baud rate is not used for USB) and reset the baud rate there.
For hard-wiring the USB connection, there is a USB breakout in the standard '5x1' pinout for red, black, white, and green USB wires. For hardwiring the TTL connection, there are breakouts for the RX and TX pin. along the edge of the PCB.