Aerex,
You cannot get the angle by reading the analog input only. The gyro outputs an analog value, approx 2.5v when not moving. It will read above 2.5v when rotating clockwise, below counterclockwise.
see page 4 of this data sheet:
http://www.analog.com/UploadedFiles/...s/ADXRS300.pdf
If you want the angle, you would need a routine to convert the rate output of the gyro (over time) to get the angle. This has already been done by EasyC/WPILib and Kevin:
http://www.kevin.org/frc/