Hello,
I assume your motor is a real DC motor, not a stepper motor (as that will not work). Use a motor that required relative high supply voltage, otherwise you need too much RPM to get sufficient voltage to overcome the threshold voltage for the LED. I hope your turbine has sufficient torque to overcome the friction in the motor.
To avoid current flowing back into the motor, you need a diode (rectifier), think of 1N400X series. As you are dealing with low voltage a so-called schottky diode (1N581x series) has less drop when it conducts, so you don't lose significant voltage. LED's are current driven devices. Applying some too high voltage will destroy them.
I would recommend you to find somebody locally with some knowledge on electronics; it will save you lots of time.
¡Mucha suerte con su proyecto de energía renovable!