CSS Help!

I need to style an ul tag with bullets that are replaced with an image. I have an id="school_list" on this one ul tag that is not on the index.htm page but on another page. I want to replace the bullets with an image only on the this one ul tag and none of the others (thus the id="school_list).
1. How do I access this one ul tag that is contained n a div id="content" / ul tag id="school_list" in the default.css file?

2. How do I replace the bullets with an image?

This is what I have that doesn't work:

#school_list ul{
list-style-image: url('abc.gif')
}

I have also tried:
div#content #school_list ul{
list-style-image: url('abc.gif')
}
AND
ul.school_list {
list-style-image: url('abc.gif')
}

Waiting for advice.......