I have one contextmenustrip control associated with treenode. I have created one menu item in contextmenustrip manually in the form itself(for example named as \"Assign\").
To add an item, you would call
myContextMenuStrip.Items.Add("Item title", null, myClickHandler);
To add a sub-menu, you take an existing item and do the same to it:
(myContextMenuStrip.Items[0] as ToolStripMenuItem).DropDownItems.Add(...)