Microphones only use 2 wires... so the microphone jack only uses 2 wires. Headphones use 3 wires, 1 ground, and 2 audio signals (Left and Right)... so the headphone jack uses 3 wires.
What's most likely happening, is the microphone jack and the headphone jack are using the same ground. All you should have to do is solder a wire from either the Left or Right (or both if you want both of the audio channels) to the Microphone. If you solder both the Left and Right channels... you will have both of the sound channels, but it won't be stereo... you'll just have both the left and right channel in each ear.
For the mobo pins... look at my diagram
Here. You will solder the "R" to Pin 2, and solder the "L" to Pin 3. The "G" can be soldered to either Pin 4 or Pin 5.
For the USB ports:
Ground goes to Ground.
D+ (Data +) goes to the Green wire.
D- (Data -) goes to the White wire.
+5v goes to +5v.
Hope that helps.