Hi so in this picture GND would be the 4th from the left top female connector hole right? What are the first two for then. What about the first bottom female connector hole?
Everything you wanted to know about the pinout of an Arduino Uno, and how the pins connect to the microcontroller/
http://www.pighixxx.com/downloads/the-definitive-arduino-pinout-diagram/
The two pins next to the USB ICSP header I think are connected to the I2C (TWI), and the other unlabeled one isn't connected. From http://arduino.cc/en/Main/arduinoBoardUno:
Revision 3 of the board has the following new features:
1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible with both the board that uses the AVR, which operates with 5V and with the Arduino Due that operates with 3.3V. The second one is a not connected pin, that is reserved for future purposes.