activeSheet.pictures.add("p1", "pics/download.jpg", 1, 6, 400, 400);
activeSheet.pictures.add("p2", "pics/download.jpg", 500, 150, 200, 300);
var pictures = activeSheet.pictures.all();
for (var i = 0; i < pictures.length; i++) {
    alert("Path of picture " + i + " is:  " + pictures[i].src())
}