cut the bottom long connector spikes 3,5,6 [color=#FF0000](warning this is irreversible)[/color]
use jumper wires to jump from 9 -> 3, 0 -> 5, 11 -> 6
Be mindful that the boards share their power supply.
Sidecarting
Mount one board on the Arduino and one board on the side disconnected.
For the disconnected board only:
use jumper wires to jump from 9 -> 3, 0 -> 5, 11 -> 6 (from the stacked board to the sidecart)
jump 5V (from the stacked board to the sidecart)
jump GND (from the stacked board to the sidecart)
Be mindful that the boards share their power supply.
Note on power supply
The above installations are valid for a max current of 2A. If you use 6A external power supply you should use 2A wires for PWM pins and 6A for 5V and GND connections. The Arduino is rated for 2A max.