Trying To Learning Some Basic JQuery?

For the moment, I'm trying to learning some basic jQuery. But when I try to create a small thing with jQuery, it doesn't work. First, I thought that it was my standard browser Chrome that was not supported.
When I tried to render it in IE and Firefox, the result stays the same.

What do I wrong ?

Here u can find the code (ps I'm working with a master page, but I don't think that this has any influence)

<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">
<script src="Scripts/jquery-1.4.1.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function () {
$("#orderedlist").addClass("tof");
$("#orderedlist > li").addClass("groen");

[Code]....