Shooting Ball

hello i have a problem to my script i have write this

 GameObject magia = GameObject.Find ("palla_di_fuoco");
     GameObject istanza = (GameObject)Instantiate(magia, magia.transform.position, magia.transform.rotation);
                 istanza.particleSystem.Play();
                 
                 int max = 50;
                 int step = 0;
                 
                 float act = istanza.transform.position.z;
                 
                 for(int i = 0; i < max; i++)
                 {
                 
                 istanza.transform.TransformDirection(new Vector3(0,0,1));
                     
                 }

i can istantiate a object (like Magic Fireball to player casting) but the script are stituated in private void and not in update. need to put this in this void reason: i use a plugin for detecting gesture like (sign)

for this. This script can run only in this void and not in update.

i have try for cicle, for increment steps and move the fireball but does move.

anyone have a solution?

(Sorry for my bad english)