Answer 1

You'll probably need to create some sort of Node class to represent the nodes in the tree:
public class Node
{
private List<Node> children = null;
private String value;
public Node(String value)
{
this.children = new ArrayList<>();
this.value = value;
}
public void addChild(Node child)
{
children.add(child);
}
}
Then to populate your tree:
public static void main(String [] args)
{
Node root = new Node("root");
root.addChild(new Node("child1"));
root.addChild(new Node("child2")); //etc.
}