Data Controls :: Bind DataGridView For Particular Childnode (ID) When Select / Click Any Particular Child Node

There are multiple child nodes coming from Database in Treeview. Also, there is a DataGridview.

I want that when I select/click any of the child node from TreeView, it should show the related data(of selected child node) in DataGridview from Database on "Page Load".

My current code is below, which only binds all the data in DataGridview and Treeview from Database:

public Form1() {
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e) {
BindGrid();
FillchildNode();

[Code] .....