<asp:TreeView ID="tvSidebarNav1" ExpandDepth="0" RootNodeStyle-ImageUrl="images/root_node.gif" LeafNodeStyle-ImageUrl="images/sub_node.gif" CollapseImageUrl="http://quickstarts.asp.net/QuickStartv20/aspnet/samples/ctrlref/navigation/TreeView/images/xp/minus.gif" ExpandImageUrl="http://quickstarts.asp.net/QuickStartv20/aspnet/samples/ctrlref/navigation/TreeView/images/xp/plus.gif" runat="server" />



 protected void Page_Load(object sender, EventArgs e)
    {
        AddDynamicPagesLinks();
    }

protected void AddDynamicPagesLinks()
    {
        try
        {
            TreeView tv = (TreeView)Page.FindControl("tvSidebarNav1");
            TreeNode newNode = new TreeNode("foo", "foo");
            tvSidebarNav1.Nodes.Add(newNode);
        }
        catch (System.Exception ex)
        {
            throw new Exception(ex.ToString());
        }
        finally
        {
            con.Dispose();
            cmd = null;
        }
    }