5-pin (top-right) has two connections. 1. 220uF capacitor and 2. resistor to .047uF capacitor to ground. 2-pin connects to 1/4 input signal wire through .047uF capacitor.
Bottom row is Ground strip. 3-pin and 4-pin are grounded by green jumpers. <NOTE: 2-pin and 3-pin are input signal + and - respectively. Switching these two will reverse the polarity of the input signal> 6-pin connects to +9V by jumper at top of image. The 7-pin is left open.
Volume control is 25k potentiometer. Green wire connected to middle lug leads to + terminal on speaker. Red wire goes to ground (typically this wire would be black since it's a ground, but this isn't one of those times) Black wire connects to board through 220uF capacitor, eventually leading to 5-pin.
Gain control wiring connections. 1-pin connects to center lug, and 8-pin connects to either end. Depending on the direction you want to turn the knob to increase the gain, clockwise or counter-clockwise.
Ground connects to center ring of 1/4" mono jack. Signal wire connects to tip portion of plug.
The speaker connects in much the same manner as the 1/4" mono input jack. Green wire carries signal from volume control, middle connection on volume potentiometer. Of course, neg terminal of speaker is connected to ground.
LED is connected by red wire connecting to the power supply, and the black to ground. When current is available, switch is on, LED will light-up. LED also serves as battery indicator.