Have you seen facebook application?
it use tabbed screen on it.
(the tab on top of it application)

this is the tabbed screen application sample[1]:

package com.rim.samples.tabcontrol;

import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FocusChangeListener;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.BasicEditField;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.SeparatorField;
import net.rim.device.api.ui.container.HorizontalFieldManager;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.container.VerticalFieldManager;

public class TabControl extends UiApplication {

	public TabControl() {
		TabControlScreen screen = new TabControlScreen();
		pushScreen(screen);
	}

	/∗∗
	∗ @param args
	∗/
	public static void main(String[] args) {
		TabControl app = new TabControl();
		app.enterEventDispatcher();
	}

	private class TabControlScreen extends MainScreen implements FocusChangeListener {

		private LabelField tab1;

		private LabelField tab2;

		private LabelField tab3;

		private LabelField spacer1;

		private LabelField spacer2;

		private VerticalFieldManager tabArea;

		private LabelField tab1Heading;

		private BasicEditField tab1Field1;

		private BasicEditField tab1Field2;

		private LabelField tab2Heading;

		private BasicEditField tab2Field1;

		private BasicEditField tab2Field2;

		private LabelField tab3Heading;

		private BasicEditField tab3Field1;

		private BasicEditField tab3Field2;

		private VerticalFieldManager tab1Manager;
		private VerticalFieldManager tab2Manager;
		private VerticalFieldManager tab3Manager;

		public TabControlScreen() {
			HorizontalFieldManager hManager = new HorizontalFieldManager();
			tab1 = new LabelField("Page 1", LabelField.FOCUSABLE | LabelField.HIGHLIGHT_SELECT);
			tab2 = new LabelField("Page 2", LabelField.FOCUSABLE | LabelField.HIGHLIGHT_SELECT);
			tab3 = new LabelField("Page 3", LabelField.FOCUSABLE | LabelField.HIGHLIGHT_SELECT);
			spacer1 = new LabelField(" | ", LabelField.NON_FOCUSABLE);
			spacer2 = new LabelField(" | ", LabelField.NON_FOCUSABLE);

			tab1.setFocusListener(this);
			tab2.setFocusListener(this);
			tab3.setFocusListener(this);
			hManager.add(tab1);
			hManager.add(spacer1);
			hManager.add(tab2);
			hManager.add(spacer2);
			hManager.add(tab3);

			add(hManager);
			add(new SeparatorField());

			tab1Manager = new VerticalFieldManager();
			tab2Manager = new VerticalFieldManager();
			tab3Manager = new VerticalFieldManager();

			tabArea = displayTab1();
			add(tabArea);

		}

		public void focusChanged(Field field, int eventType) {
			if (tabArea != null) {
				if (eventType == FOCUS_GAINED) {
					if (field == tab1) {
						System.out.println("Switch to Tab 1");
						delete(tabArea);
						tabArea = displayTab1();
						add(tabArea);
					} else if (field == tab2) {
						System.out.println("Switch to Tab 2");
						System.out.println("Switch to Tab 1");
						delete(tabArea);
						tabArea = displayTab2();
						add(tabArea);
					} else if (field == tab3) {
						System.out.println("Switch to Tab 3");
						System.out.println("Switch to Tab 1");
						delete(tabArea);
						tabArea = displayTab3();
						add(tabArea);
					}
				}
			}

		}

		public VerticalFieldManager displayTab1() {
			if (tab1Heading == null) {
				tab1Heading = new LabelField("Registration");
				tab1Manager.add(tab1Heading);
			}
			if (tab1Field1 == null) {
				tab1Field1 = new BasicEditField("Username: ", "");
				tab1Manager.add(tab1Field1);
			}
			if (tab1Field2 == null) {
				tab1Field2 = new BasicEditField("Password: ", "");
				tab1Manager.add(tab1Field2);
			}
			return tab1Manager;
		}

		public VerticalFieldManager displayTab2() {
			if (tab2Heading == null) {
				tab2Heading = new LabelField("Password Recovery");
				tab2Manager.add(tab2Heading);
			}
			if (tab2Field1 == null) {
				tab2Field1 = new BasicEditField("Security Question: ", "Mother's Maiden Name?");
				tab2Manager.add(tab2Field1);
			}
			if (tab2Field2 == null) {
				tab2Field2 = new BasicEditField("Password: ", "");
				tab2Manager.add(tab2Field2);
			}
			return tab2Manager;
		}

		public VerticalFieldManager displayTab3() {
			if (tab3Heading == null) {
				tab3Heading = new LabelField("Interests");
				tab3Manager.add(tab3Heading);
			}
			if (tab3Field1 == null) {
				tab3Field1 = new BasicEditField("Hobbies: ", "");
				tab3Manager.add(tab3Field1);
			}
			if (tab3Field2 == null) {
				tab3Field2 = new BasicEditField("Memberships: ", "");
				tab3Manager.add(tab3Field2);
			}
			return tab3Manager;
		}

	}

}

[1] http://www.blackberry.com/knowledgecenterpublic/livelink.exe/fetch/2000/348583/800332/800505/800508/How_To_-_Create_tabbed_view_screens.html?nodeid=1357482&vernum=0