Creating Java tabbed web browser - help urgently needed

[tecna_enchantix]

Hi

i am doing a 2nd year Java course, and have to create a tabbed web browser in Java.however i cant use inbuilt classes,like JTabbedPane,DefaultMutableTreeNode etc. i have to make everything myself, i am trying not to freak out.

The first part was to create a circular list which will be used to implement the tabs. This is the given circular list ADT which i had to implement:

package cs214.lists;

import cs214.common.Position;

/**
 * Interface for a circular linked list. The list has a single access point,
 * called the cursor, which may be adjusted to access the data in the list.
 * 
 * @param <E>
 *            the type of data to store at each list position.
 */
public interface CircularListADT<E> extends Iterable<E> {

	/**
	 * Returns the number of elements (alternatively, positions) in the list.
	 * 
	 * @return the number of elements in the list.
	 */
	public int size();

	/**
	 * Tests whether the list is empty.
	 * 
	 * @return <code>true</code> if the list is empty, and <code>false</code> if
	 *         it is not.
	 */
	public boolean isEmpty();

	/**
	 * Returns the cursor position in the list.
	 * 
	 * @return the cursor position.
	 * @throws EmptyListException
	 *             if the list is empty.
	 */
	public Position<E> cursor() throws EmptyListException;

	/**
	 * Removes the cursor position from the list, and returns its element. The
	 * cursor is advanced to the next position in the list, if there is one.
	 * 
	 * @return the element stored in the removed position.
	 * @throws EmptyListException
	 *             if the list is empty.
	 */
	public E remove() throws EmptyListException;

	/**
	 * Adds a new position containing the specified element to the list. If the
	 * list is non-empty, the position is added directly after the current
	 * cursor; if the list is empty, it becomes the only, first element and
	 * cursor.
	 * 
	 * @param element
	 *            the element to store at the new position.
	 */
	public void add(E element);

	/**
	 * Moves the cursor to the next position in the list.
	 * 
	 * @throws EmptyListException
	 *             if the list is empty.
	 */
	public void advance() throws EmptyListException;

	/**
	 * Moves the cursor to the previous position in the list.
	 * 
	 * @throws EmptyListException
	 *             if the list is empty.
	 */
	public void retreat() throws EmptyListException;

}

I implemented this in a Circular List file:

package cs214.lists;

import cs214.common.Position;
import cs214.lists.CNode;

import java.util.Iterator;
import java.lang.UnsupportedOperationException;

//import cs214.lists.CNode.Node;

public class CircularList<E> implements CircularListADT<E> {

	protected int size;
	protected CNode<E> cursor = null;
	protected CLIterator <E>it;

	public CircularList(){
		size = 0;
	}
	public boolean isEmpty() {
		
		return cursor == null;
	}

	
	public int size() {
		return this.size;

	}

	public Position<E> cursor() throws EmptyListException {
		
		if (cursor == null) {
			throw new EmptyListException("The list is empty.");
		}
		return cursor;

	}

	public E remove() throws EmptyListException {
		
		CNode<E> n = cursor.getPrevious();
		CNode<E>m = cursor.getNext(); 
		
		if (cursor == null) {
			throw new EmptyListException("The list is empty.");
		}

		else {
			n.setPrevious(m);
			m.setNext(n);
			
			cursor.setPrevious(null);
			cursor.setNext(null);
			
			size--;
			/*n = cursor;
			n.next = cursor.next;
			cursor = n.next;*/
		}	
		
		return cursor.value;
	}
	
	public void add(E element) {

		CNode<E> n = new CNode<E>(element,cursor,cursor.getPrevious());

		if (cursor == null) {
			n.next = n;
			cursor = n;
		}

		else {
			n.next = cursor.next;
			cursor.next = n;
			cursor = n;

		}
	}

	public void advance() throws EmptyListException {
		
		if (cursor == null) {
			throw new EmptyListException("The list is empty.");
		}

		else {
			it = new CLIterator<E>(cursor);
			cursor = cursor.next;
		}

	}
	
	public void retreat() throws EmptyListException{
		
		if (cursor == null) {
			throw new EmptyListException("The list is empty.");
		}
	}
	
/*	public Iterator<E> getIterator()	{
		return it;
	}
*/
	public Iterator<E> iterator(){
		
		return new CLIterator<E>(cursor);
	}

	 class CLIterator<E> implements Iterator<E> {
		 CNode<E> cursor;
		 
		public CLIterator(CNode<E> cursor)	{
			this.cursor = cursor;
		}

		@Override
		public boolean hasNext() {
			
			return false;
		}

		@Override
		public E next() {
			cursor = cursor.getNext();
			return cursor.element();
		}

	
		public void remove() throws UnsupportedOperationException{
			if (cursor ==null){
				throw new UnsupportedOperationException();
			}
			
			
		}
	}
}

This is the Position interface:

package cs214.common;

/**
 * A position in a relatively-defined data structure. Allows a user access to an
 * element stored at the position, without breaking encapsulation and exposing
 * implementation dependent links to other positions.
 * 
 * @param <E>
 *            the type of element stored at the position.
 */
public interface Position<E> {

	/**
	 * Returns the element associated with this position.
	 * 
	 * @return the element associated with this position.
	 */
	public E element();

}

and the CNode class which i created to define nodes in the circular list:

package cs214.lists;

import cs214.common.Position;

public class CNode<E> implements Position<E> {

	protected E value;
	protected CNode<E> next,prev;


	public CNode(E element, CNode<E> n, CNode<E> p){
		value = element;
		next = n;
		prev = p;
	}

	//public CNode(E element2) {
	// TODO Auto-generated constructor stub
	//}

	public E element() {
		return value;
	}

	public CNode<E> getPrevious(){
		return prev;
	}

	public CNode<E> getNext(){
		return next;
	}

	public void setElement(E newElement){
		value = newElement;
	}

	public void setPrevious(CNode<E> newPrevious){
		prev = newPrevious;
	}

	public void setNext(CNode<E> newNext){
		next = newNext;
	}
	
	public String toString(){
		return"This is a node and this is what is inside it " + value;
	}
}

My problem is, i dont know how to test if this actually works. Im supposed to make a simple GUI which will create a new tab, close it etc. attached is the actual question. I would appreciate any help at all, because i cant move on to the next part if i dont fix this asap.