عندما اضغط كليك يمين على node تنسدل قائمه ,كيف افعلها؟؟؟؟

private void Form1_Load(object sender, EventArgs e)
{
TreeNode treeNode1 = new TreeNode();
treeNode1.Text = "father";
treeView1.Nodes.Add(treeNode1);
treeNode1.ContextMenuStrip = contextMenuStrip1;
}
//this event for items of contextmenustrip1

private void addNewNodeToolStripMenuItem_Click(object sender, EventArgs e)
{
TreeNode treeNode2 = new TreeNode();
treeNode2.Text = "Child";

selectedNode.Nodes.Add(treeNode2);
selectedNode.ContextMenuStrip = contextMenuStrip1;
}

private void treeView1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Right)
{
selectedNode = treeView1.GetNodeAt(e.X, e.Y);
}

}