Hi Rupali,
You can use javascript to achieve this
<asp:treeview id="TreeView1" runat="server" xmlns:asp="#unknown">
<nodes>
<asp:treenode navigateurl="javascript:nav();" text="Hello"></asp:treenode>
</nodes>
</asp:treeview>
Javascript function
<script language="text/javascript">
function nav() {
document.getElementById('iframe1').src = "getdata.aspx";
}
</script></script>
You can even set NavigateUrl property from the code behind in .vb file
Hope this will help :)
Thanks
Vinod