Microsoft.Web.UI.WebControls.TreeView Treeview11 

public void PopulateTree()
{
   TreeNode nodeProdDetail, nodeProdMaster;
   nodeProdMaster      = new TreeNode();
   nodeProdMaster.Text = "Master1";
   nodeProdMaster.ID   = "1";

   nodeProdDetail             = new TreeNode();
   nodeProdDetail.Text        = "Detail1";
   nodeProdDetail.ID          = "1.1";
   nodeProdDetail.NavigateUrl = "SomePage.aspx";
   nodeProdMaster.Nodes.Add(nodeProdDetail);

   Treeview1.Nodes.Add(nodeProdMaster);

   nodeProdMaster      = new TreeNode();
   nodeProdMaster.Text = "Master2";
   nodeProdMaster.ID   = "2";

   nodeProdDetail             = new TreeNode();
   nodeProdDetail.Text        = "Detail2";
   nodeProdDetail.ID          = "2.1";
   nodeProdDetail.NavigateUrl = "SomeOtherPage.aspx";
   nodeProdMaster.Nodes.Add(nodeProdDetail);

   Treeview1.Nodes.Add(nodeProdMaster);
}