how to rotate object infinitely in unity with given speed code example

Example 1: how to set a screen rotation in unity

public class Example : MonoBehaviour
{
    // Start in landscape mode
    void Start()
    {
        Screen.orientation = ScreenOrientation.LandscapeLeft;
    }
}

Example 2: c# how to make object rotate forever

//Use FixedUpdate instead of Update for physics, rotation, and movement.
void FixedUpdate()
    {
        laserPointer.Rotate(x, y, z);
  		//Use your own rotation values to replace x, y and z.
    }