I need to test a little later to confirm, so don't take me to the bank just yet, but looks like pin 1 of the opto (rightmost pin, side closest to LEDs) is the 3.3V pin, pin 2 (next pin to the left) is the connection to the LED.
If you are hesitant to power it up and take some readings, one thing you can do is a quick continuity check. I'd verify continuity from the pic pins for LEDs 4 and 6 to one side of the LED (traces are on top of the board). Safest way if you're hesitant is to remove the pic chip, and test from the socket (i.e, top of the board), as that will also confirm you didn't bend a pin under the socket. The common point between those two channels points you back to the pic and the pic socket.
If you have continuity, chips are in correctly, LEDs are in correctly, you really then need to get some voltage readings to see what is going on.