swap depths help

Ok I have a banner and it loadmovies 3 banners into it. I want the main banner to stay on top. I was told to use swap depths but I don't know how with loadmovie. Here's my code.


_root.createEmptyMovieClip("container", 1);
loadMovie("banner1.swf", "container");

container._x = 0;
container._y = 0 ;


but.onPress = function () {
_root.createEmptyMovieClip("container", 1);
loadMovie("banner1.swf", "container");
container._x = 0;
container._y = 0;

but.gotoAndStop(2);
but3.gotoAndStop(1);
but2.gotoAndStop(1)

}
but2.onPress = function () {
_root.createEmptyMovieClip("container", 1);
loadMovie("banner2.swf", "container");
but2.gotoAndStop(2);
but.gotoAndStop(1);
but3.gotoAndStop(1)

container._x = 0;
container._y = 0;
}
but3.onPress = function () {
_root.createEmptyMovieClip("container", 1);
loadMovie("banner3.swf", "container");
container._x = 0;
container._y = 0;
but3.gotoAndStop(2);
but.gotoAndStop(1);
but2.gotoAndStop(1)
}