Add OnlineModeFrame class.

src/OnlineModeFrame.java

+import javax.swing.*;
+import java.awt.*;
+
+public class OnlineModeFrame extends JFrame {
+    private JComboBox serverBox;
+    private JPanel serverChoosePanel;
+    private JPanel gamesPanel;
+    private JButton playButton;
+    private JButton createGame;
+
+    public OnlineModeFrame() {
+        setBackground(Color.WHITE);
+        setResizable(false);
+        setLayout(new BorderLayout());
+        setBounds(400, 200, 900, 600);
+        initServerList();
+        initGamesPanel();
+        setVisible(true);
+
+    }
+
+}