Read the seminal article "CSS Design: Taming Lists" at http://www.alistapart.com/articles/taminglists/ and become a master on the subject.
You will have to add the necessary CSS to your theme (usually in style.css unless you are using the Zen theme, in which case {name-of-{theme | subtheme}.css) after making sure there exists an id or class DIV wrapping the list.
If you cannot understand the CSS discussion, bone up by reading one of the O'Reilly classics on the subject, or else online, for example, at http://reference.sitepoint.com/css.
You or someone in your organization must have at least a conversational knowledge of CSS to be successful in Drupal, as the passage from Drupal 5 to 6 to 7 leads towards more and more of the theming being controlled by CSS.
Victor Kane
http://awebfactory.com.ar