Continuous Random Animations

I just want to create sparkling stars at random. I can place the twinkling star to one random location but that is fixed while i close the window. I want to place the star at different random locations in the same window. I googled and i found action script code but that dosnt useful for a movieclip animation.
code:
onClipEvent(enterFrame)
{
_x=_x=random(250);
_y=_y=random(250);
}
by this actionscript to the movie clip, I can executes continuously but it is very fast one.
code:
onClipEvent(load){
_x= random(200);
_y= random(200);
}
this choses random location but the location is static while i close the window.


I want to Place the movieclip at different location just after finishing of the previous one. How to do that one?

Code:

---

onClipEvent (load) {
        _x = _x = random(180);
        _y = _y = random(400);
        _alpha = 80 + random(20);
        _xscale = _yscale = 80 + random(80);
        ct = random(100);
}
onClipEvent (enterFrame) {
        if (ct <= 0) {
                if (_alpha <= 0) {
                        _x = random(180);
                        _y = random(400);
                        _alpha = 80 + random(20);
                        _xscale = _yscale = 80 + random(80);
                        ct = 50 + random(50);
                } else {
                        _alpha = _alpha - 2;
                }
        } else {
                ct = ct - 1;
        }
}

---

Thank You very much for that code. Now only I understand a little bit about onClipEvent. I was tried to make a starry night using the same movieclip. i succeeded a little bit. But I am not satisfied. I just make duplicates of my movie clip 50 times and places thats at random positions by this code.
code::
for(var i=1;i<=50;i++){
newname = "star1"+i;
star1.duplicateMovieClip(newname,i);
newname._x = random(750);
newname._y = random(550);
}
star1 is my instance name in properties. I got 50 stars at random positions when i set actionscript code as
onClipEvent(load){
_x= random(800);
_y= random(600);
_alpha = 100;
}
onClipEvent(enterFrame)
{
if(_alpha<=0){
_x = random(700);
_y = random(599);
_alpha = 100;
}
else {
_alpha--;
}
}
all stars just dimmed slowly and disperses, then a new set of stars appears. But all the 50 stars starts and disperses at the same time.
I want to chose some of stars at random to start at beginning, before finishing of the movieclip the second set is to be started. How to set such a condition and where to set. pls refer the attached file.

Code:

---

// place on main timeline, delete existing onClipEvent codes
var tID;
var numStars = 50;
var stars = [];

star1.onEnterFrame = function() {
        if (random(50) == 0) {
                mc = stars[random(stars.length - 1)];
                mc._x = random(550);
                mc._y = random(400);
                mc._alpha = random(90);
        }
};

makeStar();

function makeStar() {
        var mc = star1.duplicateMovieClip("s" + numStars, numStars--);
        mc._x = random(550);
        mc._y = random(400);
        mc._alpha = random(90);
        stars.push(mc);
        if (numStars > 1) {
                tID = setTimeout(makeStar, random(53));
        } else {
                clearTimeout(tID);
        }
}

---

yep the code works perfect but i am unable to find meaning of these codes. Actually what these code does? Can you please explain a little bit how it is executed?