you should use tree view in asp.net like below :
<asp:treeview id="TreeView2" runat="server" datasourceid="XmlDataSource1" font-names="Tahoma" xmlns:asp="#unknown">
Font-Size="8pt" ImageSet="BulletedList3" LineImagesFolder="/../../TreeLineImages"
SelectedNodeStyle-Font-Bold="true" SelectedNodeStyle-ForeColor="Red" ShowLines="True"
OnSelectedNodeChanged="TreeView2_SelectedNodeChanged" ExpandDepth="1">
<databindings>
<asp:treenodebinding datamember="Node" textfield="Name" valuefield="ID" />
</databindings>
</asp:treeview>