Migrating a project from AS2 to AS3, need help with attachMovie()

Here’s what I have for one part. It’s pulling in movieclips from another page. Any idea what to replace attachMovie with? Thanks!

function loadPage(whatPage){
    this.DisplayObject.y = 100;
    attachMovie(whatPage, "mainPage", 5555, {alpha:100, scaleX:100,scaleY:100 , x:0 , y:0, id:whatPage} );
    mainPage.gotoAndStop(root.currentScenerio + 1);
    trace("Viewing this page: " + whatPage);
}
loadPage("mainInfo");