What you've done there is created an absolute-relative path
See how there's an extra / right at the start of the image path? That's actually telling the browser to start looking for the image from the root directory (and on your computer, that's likely to be where the operating system is installed), and that will be the case regardless of where the web page is.
So lets get back to relative paths and remove that beginning slash;
This is now telling the browser to look for your images, 2 levels deep - inside a folder called "GallerySlider2" that is in turn inside another folder called "images". In this case your web page would be sat alongside the "images" folder. So to get this to work, you need to make sure that there is an "images" folder sat alongside your web page, and within that there needs to be a "GallerySlider2" folder, with the "galleryslider1.jpg" pic sat inside of that.
The script image array takes the following format;
No <li> or <img> tags required.
["path_to_image", "optional_link", "optional_linktarget", "optional_textdescription"]
The critical one is the first parameter - the path to your image - all the rest can be blanked out if you don't need them;
The demo references images on another website and that's fine too. Thats an absolute path - with the http:// part at the start
["path_to_image", "", "", ""]
I think it will help if you read up on paths as it will really help you understand what you're doing -this should help : http://webdesign.about.com/od/beginn.../aa040502a.htm