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If you have a binary search tree:-
Consider making the Node a private inner class in the Tree class. That is because you can consider a node to be part of a tree and not to be needed outside the tree. You can read about inner classes
here.
When you create a new tree it has no nodes.
When you add your first value you create a new node often called root to contain it.
When you add subsequent values you consider whether they are greater or less than the value in the node and add them left or right accordingly.
I am not sure a file system matches a binary search because each level can contain an arbitrary number of elements whereas a binary tree usually contains up to two at each level. I think you need a Collection of nodes in each node; remember that a List would permit you to have two elements with the same name. You can move things up and down in Lists by removing and re‑inserting elements into the List.