The slide switch connects to the EN and GND pins the Adafruit PowerBoost1000C.
The 2500mAh batteries plugs into the JST connector on the PowerBoost1000C. You can charge the battery by connecting a microUSB cable.
Raspberry Pi 2:
Positive+ and -Negative pins on the PowerBoost1000C connect to the Pi on GPIO #2 for 5V power and GPIO # 6 for ground.
+Positive and -Negative pins on the Driver Board connect from 5V and GND labeled on the Display Driver to the Pi on GPIO pins #4 for Power and #9 for Ground