Script block

1

i am trying to make a movie clip move continuously in a random way on a bar/

for(i=0; i < 1600; i++){

aiurea = -10 + Math.floor(Math.random() * 20);
if (light._y &lt; Stage.height){
    this.light.tween("_y", light._y, airuea*500  , aiurea);
    trace(aiurea);
}
else{
    light._y=0;
    trace("dincolo");
}

}

i know my code is wrong. and i have the wrong aproach .but i am new to this and this is the best i come up with.

can i get some hints on how to do this ??