D3TreeView Widget and Tree view structure

I am using D3TreeView widget for creating tree view structure, but every time when we are adding nodes in the tree structure,(it will ask the parent node where we need to add the new node),it is adding the new node only under the main parent node. How to make a multi level tree? I have also refered the D3TreeView Demo project , but in that also we are not able to add the new node in the tree structure. Could anyone please tell where to make the changes so that we can create a multi-level tree structure, or is there any other way with which we can create a multi-level tree structure?