Adding external wiring

[mahtDFR]

Hello there, bought one of these from your Tindie.

I'd like to use external wires to power this. I take it I can solder some to the test points, but I'm not sure which is which. I can see there's a schematic but my knowledge of these is rusty.

Is there a diagram that shows the connections? And which voltage should it use? 3V?