GY-50 L3G4200 gyroscope

You should do this step by step.

What voltage needs your breakout board ? 5V or 3.3V ?
Are there pull-up resistors on your breakout board for the SDA and SLC lines ?
I check the pictures, and there is a voltage regulator on the breakout board for 3.3V. So you may connect +5V to Vcc. It seems that the pull-up resistors for the SDA and SCL are 10k. It is safer if they would be 4k7. So you could try it as it is, and add later two extra 10k resistors from the SDA and SCL lines to the 3.3V (not the 5V !).

If you have solved that, run the i2c_scanner to see if the sensor can be detected : http://arduino.cc/playground/Main/I2cScanner
If the i2c_scanner can find your sensor, you should find a good sketch for the sensor.