Continuous Rotation of an object Script

How i can make continuous rotation of an object from the x to the z axis ? can someone help me please ? ? as here in the picture http://s8.postimg.org/e875n50yt/ROTATION.jpg
http://s21.postimg.org/3o5ftt2kn/rotation1.jpg
http://s14.postimg.org/lmmf8o9u9/rotation2.jpg

I think you are asking for:

var speed = 55.0;

function Update() {
    transform.Rotate(0.0, speed * Time.deltaTime, 0.0);
}