Hi,
Try this-
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.5.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function () {
$("table tr:odd").css("background-color", "red");
$("table tr:even").css("background-color", "gray");
});
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:DataList ID="DataList1" runat="server" RepeatColumns="1" RepeatDirection="Vertical">
<ItemTemplate>
<div>
<img src='<%#Eval("Url")%>' /><br />
<span><%#Eval("Caption")%></span>
</div>
</ItemTemplate>
</asp:DataList>
</form>
</body>
</html>