Hi Shud,
Refer below sample.
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <style type="text/css">
        .Star
        {
            background-image: url(images/Star.gif);
            height: 17px;
            width: 17px;
        }
        .WaitingStar
        {
            background-image: url(images/WaitingStar.gif);
            height: 17px;
            width: 17px;
        }
        .FilledStar
        {
            background-image: url(images/FilledStar.gif);
            height: 17px;
            width: 17px;
        }
    </style>
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    <script type="text/javascript">
        function Show() {
            setTimeout('showData()', 1000);
        };
        function showData() {
            document.getElementById("<%=Rating1.ClientID %>").style.display = "block";
            document.getElementById("<%=lblRatingStatus.ClientID %>").style.display = "block";
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <cc1:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
    </cc1:ToolkitScriptManager>
    <cc1:Rating ID="Rating1" AutoPostBack="true" runat="server" Style="display: none"
        CssClass="rating" StarCssClass="Star" WaitingStarCssClass="WaitingStar" EmptyStarCssClass="Star"
        FilledStarCssClass="FilledStar">
    </cc1:Rating>
    <br />
    <asp:Label ID="lblRatingStatus" runat="server" Text="" Style="display: none"> </asp:Label>
    <br />
    <asp:Button Text="Show Rating" runat="server" OnClick="Show" />
    </form>
</body>
</html>
Code
C#
protected void Show(object sender, EventArgs e)
{
    Rating1.CurrentRating = 2;
    lblRatingStatus.Text = string.Format("{0} Users have rated. Average Rating {1}", 5, 1);
    ClientScript.RegisterStartupScript(this.GetType(), "alert", "Show();", true);
}
VB.Net
Protected Sub Show(ByVal sender As Object, ByVal e As EventArgs)
    Rating1.CurrentRating = 2
    lblRatingStatus.Text = String.Format("{0} Users have rated. Average Rating {1}", 5, 1)
    ClientScript.RegisterStartupScript(Me.GetType(), "alert", "Show();", True)
End Sub
Screenshot
