Follow the circuit diagram above to reference the connections for each component. The parts are not to scale but should give you a visual idea of the circuit.
Positive > UBEC Positive
Negative > UBEC Negative
GND > UBEC negative
+5V USB > UBEC postive
The positive wire on the battery is connected to the slide switch and postive wire on the UBEC (from the short wires). The short negative wire from the ubec is connected to the negative wire on the battery holder.
The +5V and GND pads next to USB port are connected to a female JST cable. A slide switch is connected to the -25mA pad on the HDMI display backpack.
Optionally plug in a micro USB cable to the HDMI display backpack to power from a batterybank or wall outlet using a USB adapter.
You can optionally convert the UBEC into a microUSB cable using an DIY connector plug. Look up the pinouts for wiring and be careful to get it right!