Hi,
There are two ways to do it. One is by handling ItemClick event, the other is by handling ItemPopulate event. For both events e.TreeNode contains the clicked node.
In order to populate the children, you just create a new node and add it to the parent node's Nodes collection:
Code: C#
EO.Web.Node child = new EO.Web.Node();
child.Text = "node text";
parent.Nodes.Add(child);
You can find more sample code in the sample project, which is installed on your machine in the form of Visual Studio projects when you install our product.
Thanks