how to capture the node value in selected node changed.

i created treeview . it works fine. but when you click + the following method will call
protected void TreeView1_TreeNodePopulate(object sender, System.Web.UI.WebControls.TreeNodeEventArgs e) {
PopulateSubLevel(Convert.ToInt32(e.Node.Value), e.Node); }

but i need while click on node (ie after +) for example : +football. 
here i will have id for football. right. so i need to capture that node value when clicking on football. so that i can call populatesublevel method. becuasue once clicked on football, it has to show on right side it's images as well as i need to expand it's tree on left side. 
please hel