how to rotate 3d model in touch using guy texture object

I want to press on guitexture which instructs 3d model to rotate

One way of doing it:

public Transform obj = null; // Reference to your model
public float speed = 5.0f; // Rotation speed

void OnGUI()
{
  if (GUI.Button(new Rect(0.0f, 0.0f, 64.0f, 16.0f), "Left"))
    obj.Rotate(-speed * Time.deltatime);
  if (GUI.Button(new Rect(70.0f, 0.0f, 64.0f, 16.0f), "Right"))
    obj.Rotate(speed * Time.deltatime);
}