应该/如何使用.slice（）在按下按钮时交换图像scr？ （用于图库中的下一个/上一个按钮）

I am stumped and could really use some help with this gallery I've been working on. I used Ivan's '4 lines of jquery gallery' tutorial to get me where I am at currently. Here's his demo which shows exactly how it all works I am stumped and could really use some help wit