problems wiht image gallery using an asp:ImageButton

I am an illustrator, and I am trying to design my  website using asp.net 2 (but unfortunatly I am not a programmer!!!) At present the pagination is a numeric pagination but for the sake of navigation I would like to add thumbnail buttons

So on the page I try to create on the left stands the main image, stored in a DetailsView control, as on the right are all the images Thumbnails, stored in a Datalist. It works pretty well, the problem is that because the ImageButton in my Datalist fires a PostBackUrl method, every time the method is called all the page (including the thumbnails) jumps up as it reloads. Any tips? Here below the code. Many thanks as usual Shirley and Mario

 

<form id="form1" runat="server">

 

  <asp:DetailsView ID="DetailsView1" runat="server" DataSourceID="AccessDataSource1"

  &nbs ...