its using mootools and not jquery, thats a shame, plenty of decent jquery sliders around, and its simple to play about with jquery,
nowt wrong with mootools, its just another jscript framework, I prefer jquery though
do a search for mootools sliders, or mootools tutorials, it'll give you a good idea on how to tweak the slider js files and the like
and if you want to add any other jscript bits to the template, you'd be best sticking with mootools for your jscript stuff seeing as the framework is already loaded
(jscript framework mootools version 1.2 is the one used on the black raven template)

<edit to add>
I have noticed somthing, you have two generator meta tags in your header, should only be one, and there's no keywords showing on the main page (thats probably because none have been set yet though)
this is the extra meta tag that you dont need
<meta name="Generator" content="TomatoCart" />