Adding a custom background changer

Hi Bytesforall

First off. Wonderful theme, its been a an absolute joy getting to know it this past months or so (a bajillion times better than constructor).

However, one thing Constructor allowed me to do was, add a custom background changer I made into the blog (http://www.theredshow.co.uk/gallerytest.html)

I have so far met with little success. I can get as far as seeing the slider so I know its seeing the CSS but but it doesn't seem to want to work when clicking the buttons. As you'll see from the source its really a very simple idea, but where in gods name do I stick the code to allow to work with my wordpress theme website (http://www.theredshow.co.uk/)

Thanks
Udapud