How to add a dialog?

I want to add a easy dialog like this:

function menuItemHandler4ClearCache(event) {
    var myDialog = app.dialogs.add({name:"Clear Cache Confirm", canCancel:true});
    with(myDialog){
        staticTexts.add({staticLabel: "Are you confrim to clear cache?"});
    }
    var myResult = myDialog.show();
    if(myResult == true){
        myDialog.destroy();
        //remove cache folder.
    }else{
        myDialog.destroy();
    }
}

But this code is not work, is any problem here?

and how to add a icon to dialog like in image?

please help me, thanks a lot!!