redirect a page in right frame using treeview

Hi
  i have a treeview in left frame and want to open a new page on click of a leaf node
   of a treeview in right frame .how.I want to do this in code behind treeview.selected node
  change event

treeview1.selectednode_CHANGEEVENT
        
 If TreeView1.SelectedNode.Value = "Masters" Then

               'Response.Redirect("Master.aspx? ...---????


        End If
how to open this page in right frame
...