a) To change the size of the slide show, go to the line
var width = 250;
and change to value of height and width to any pixel size yo want.
var height = 100;
b) To set images for slideshow.
Go to the line
imgAr1 = "dir1/image-1.jpg";
Replace the values "dir1/image-1.jpg" and "dir1/image-2.jpg" to the path of your pictures.
you can add any number of photo in to the array. To add one more picture
imgAr1 = "dir1/image-2.jpg";
imgAr1 = "dir1/image-3.jpg";
more image can be added as imgAr1, imgAr1, imgAr1, so on....