First Create a XML as App_Data/Advertisements.xml

<?xmlversion=”1.0″encoding=”utf-8″ ?>
<Advertisements>
<Ad>
<ImageUrl>~/images/dnc.jpg</ImageUrl>
<NavigateUrl>http://www.dotnetcurry.com</NavigateUrl>
<AlternateText>DotNetCurry Home Page</AlternateText>
<Impressions>40</Impressions>
<Keyword>small</Keyword>
</Ad>
<Ad>
<ImageUrl>~/images/ssc.jpg</ImageUrl>
<NavigateUrl>http://www.sqlservercurry.com</NavigateUrl>
<AlternateText>SQL Server Curry Home Page</AlternateText>
<Impressions>20</Impressions>
<Keyword>small</Keyword>
</Ad>
<Ad>
<ImageUrl>~/images/writeforus.jpg</ImageUrl>
<Width>300</Width>
<Height>50</Height>
<NavigateUrl>http://www.dotnetcurry.com/writeforus.aspx</NavigateUrl>
<AlternateText>dotnetcurry.com Write For Us</AlternateText>
<Impressions>40</Impressions>
<Keyword>small</Keyword>
</Ad>
</Advertisements>

Code your ASPX as below
<form id=”form1″ runat=”server”>
<div>
<asp:ScriptManager ID=”ScriptManager1″ runat=”server” />
<asp:Timer ID=”Timer1″ Interval=”2000″ runat=”server” />

<asp:UpdatePanel ID=”up1″ runat=”server”>
<Triggers>
<asp:AsyncPostBackTrigger ControlID=”Timer1″ EventName=”Tick” />
</Triggers>
<ContentTemplate>
<asp:AdRotator
id=”AdRotator1″
AdvertisementFile=”~/App_Data/Advertisements.xml”
KeywordFilter=”small”
Runat=”server” />
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>