u should use adrotator control and xml file
and this xml file shold have these tags
="1.0"="utf-8"
<Advertisements>
<Ad>
<ImageUrl></ImageUrl>
<AlternateText></AlternateText>
<NavigateUrl></NavigateUrl>
<Impression></Impression>
</Ad>
</Advertisements>
in between this ImageUrl write image path like images/01.jpg
if picture not found it will show the path u type in AlternateText
after that use adrotator and select this file with adrotator.