Операции с деревом проконсультируйте

private void treeView1_AfterCheck(object sender, TreeViewEventArgs e)
        {
            if(e.Node.Checked) 
        }

private void CheckChildren(TreeNode node, bool setCheck)
{
     foreach (TreeNode child in node.Nodes)
     {
          child.Checked = setCheck;
          CheckChildren(child);
     }
}

private void treeView1_AfterCheck(object sender, TreeViewEventArgs e)
{
 for (int i = 0; i < e.Node.Nodes.Count; i++) e.Node.Nodes[i].Checked = e.Node.Checked;
}

List<TreeNode> checkedNodeList = new List<TreeNode>();
foreach (TreeNode node in treeView1.Nodes)
{
   if (node.Checked)
      checkedNodeList.Add(node);
   checkedNodeList.AddRange(GetCheckedChildren(node));
}
 
//...
private List<TreeNode> GetCheckedChildren(TreeNode node)
{
   List<TreeNode> checkedNodeList = new List<TreeNode>();
   foreach (TreeNode child in node.Nodes)
   {
      if (child.Checked)
         checkedNodeList.Add(child);
      checkedNodeList.AddRange(GetCheckedChildren(node));
   }
 
   return checkedNodeList;
}

checkedNodeList.AddRange(GetCheckedChildren(child));

 foreach (var l in checkedNodeList)
            {
                textBox1.AppendText(l.FullPath+Environment.NewLine);
            }

if (child.Checked && child.Nodes.Count == 0)
   checkedNodeList.Add(child);