See: http://download.oracle.com/javafx/2.0/api/javafx/scene/control/TabPane.html

Missing " in tab.setText("new tab); and Extra semicolon in tab.setContent(new Rectangle(200,200, Color.LIGHTSTEELBLUE););

 TabPane tabPane = new TabPane();
 Tab tab = new Tab();
 tab.setText("new tab);
 tab.setContent(new Rectangle(200,200, Color.LIGHTSTEELBLUE););
 tabPane.getTabs().add(tab);