diff --git a/src/frames/IMainFrame.java b/src/frames/IMainFrame.java
new file mode 100644
index 0000000..678a2b1
--- /dev/null
+++ b/src/frames/IMainFrame.java
@@ -0,0 +1,10 @@
+package frames;
+
+import javax.swing.JPanel;
+
+// -------------------------------------------------------------------------
+//
+public interface IMainFrame {
+	void showMainPanel(JPanel nowPanel);
+	void showHistoryPanel(JPanel nowPanel, int index);
+}
diff --git a/src/frames/MainFrame.java b/src/frames/MainFrame.java
index af9b221..485a2a0 100644
--- a/src/frames/MainFrame.java
+++ b/src/frames/MainFrame.java
@@ -12,7 +12,7 @@
 
 //-------------------------------------------------------------------------
 // 
-public class MainFrame extends JFrame {
+public class MainFrame extends JFrame implements IMainFrame {
 
 	// field
 	private State state;
diff --git a/src/panels/MainPanel.java b/src/panels/MainPanel.java
index 5a691bd..c2e566c 100644
--- a/src/panels/MainPanel.java
+++ b/src/panels/MainPanel.java
@@ -20,6 +20,7 @@
 import javax.swing.table.DefaultTableModel;
 import javax.swing.table.TableModel;
 
+import frames.IMainFrame;
 import frames.MainFrame;
 import frames.State;
 import resources.Customer;
@@ -30,7 +31,7 @@
 public class MainPanel extends JPanel {
 
 	// frame
-	private MainFrame mainFrame;
+	private IMainFrame mainFrame;
 
 	// model
 	private CustomersModel model;
@@ -50,7 +51,7 @@
 	// constructor
 	// -------------------------------------------------------------------------
 	//
-	public MainPanel(MainFrame mainFrame, CustomersModel model) {
+	public MainPanel(IMainFrame mainFrame, CustomersModel model) {
 
 		super(new BorderLayout());
 
@@ -114,7 +115,7 @@
 	// private
 	// -------------------------------------------------------------------------
 	//
-	private void transitionToHistory(MainFrame mainFrame, int index) {
+	private void transitionToHistory(IMainFrame mainFrame, int index) {
 		mainFrame.showHistoryPanel(this, index);
 	}
 
@@ -162,7 +163,7 @@
 
 	// -------------------------------------------------------------------------
 	// transition to history
-	private class ShowHistoryActionHandler implements ActionListener, EventListener {
+	private class ShowHistoryActionHandler implements ActionListener {
 
 		// -------------------------------------------------------------------------
 		//
diff --git a/src/panels/ShowHistoryPanel.java b/src/panels/ShowHistoryPanel.java
index ff77477..acd6a7d 100644
--- a/src/panels/ShowHistoryPanel.java
+++ b/src/panels/ShowHistoryPanel.java
@@ -1,20 +1,29 @@
 package panels;
 
 import java.awt.BorderLayout;
+import java.awt.Dimension;
 import java.awt.FlowLayout;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
+import java.text.DecimalFormat;
 import java.util.ArrayList;
 import java.util.HashMap;
 
+import javax.swing.BoxLayout;
 import javax.swing.DefaultListModel;
 import javax.swing.JButton;
+import javax.swing.JComponent;
+import javax.swing.JFormattedTextField;
+import javax.swing.JLabel;
 import javax.swing.JList;
 import javax.swing.JPanel;
 import javax.swing.JScrollPane;
 import javax.swing.JTable;
+import javax.swing.JTextField;
+import javax.swing.border.Border;
 import javax.swing.table.DefaultTableModel;
 
+import frames.IMainFrame;
 import frames.MainFrame;
 import resources.Customer;
 import resources.CustomersModel;
@@ -24,7 +33,7 @@
 public class ShowHistoryPanel extends JPanel {
 
 	// frame
-	private MainFrame mainFrame;
+	private IMainFrame mainFrame;
 
 	// model
 	private Customer selectedCustomer;
@@ -35,6 +44,8 @@
 	private DefaultListModel<Integer> historiesListModel;
 
 	// buttons
+	private JLabel nameLabel;
+	private JTextField textField;
 	private JButton backButton;
 	private JButton payButton;
 
@@ -43,7 +54,7 @@
 	// constructor
 	// -------------------------------------------------------------------------
 	//
-	public ShowHistoryPanel(MainFrame mainFrame, CustomersModel model) {
+	public ShowHistoryPanel(IMainFrame mainFrame, CustomersModel model) {
 		super(new BorderLayout());
 
 		// initialize frame
@@ -56,22 +67,35 @@
 		historiesListModel = new DefaultListModel();
 		historiesList = new JList(historiesListModel);
 
-		// add buttons
-		JPanel buttonPane = new JPanel();
-		backButton = new JButton("Back");
+//		this.setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
+
+		// add labels
+		nameLabel = new JLabel();
+		add(nameLabel, BorderLayout.NORTH);
+
+		// add scroll menu
+		JScrollPane scrollPanel = new JScrollPane(historiesList);
+		add(scrollPanel, BorderLayout.CENTER);
+		
+		// add payment fields
+		textField = new JTextField(1);
 		payButton = new JButton("Payment");
-		buttonPane.add(backButton);
-		buttonPane.add(payButton);
-		add(buttonPane, BorderLayout.SOUTH);
+
+		JPanel panel = new JPanel();
+		panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
+		panel.add(payButton);
+		panel.add(textField, new Dimension(1,1));
+		add(panel);
+
+		// add back button
+		backButton = new JButton("Back");
+		add(backButton, BorderLayout.NORTH);
+		
 
 		// add listener
 		backButton.addActionListener(new BackActionHandler());
 		payButton.addActionListener(new PaymentActionHandler());
 
-		// add scroll menu
-		JScrollPane scrollPanel = new JScrollPane(historiesList);
-		add(scrollPanel, BorderLayout.NORTH);
-
 	}
 
 	// -------------------------------------------------------------------------
@@ -81,8 +105,11 @@
 	//
 	public void updateListModelByIndex(int index) {
 		selectedCustomer = model.getCustomers().get(index);
+
 		historiesListModel.removeAllElements();
 		historiesListModel.addAll(model.getCustomers().get(index).getHistory());
+
+		nameLabel.setText("name: " + selectedCustomer.getName());
 	}
 
 	// -------------------------------------------------------------------------
@@ -90,7 +117,7 @@
 	// private
 	// -------------------------------------------------------------------------
 	//
-	private void transitionToMain(MainFrame mainFrame) {
+	private void transitionToMain(IMainFrame mainFrame) {
 		mainFrame.showMainPanel(this);
 	}
 
@@ -112,10 +139,18 @@
 	// payment button's event
 	private class PaymentActionHandler implements ActionListener {
 		public void actionPerformed(ActionEvent e) {
-			selectedCustomer.purchase(1000);
+
+			String text = textField.getText();
+
+			// filtering
+			if (!text.matches("^[0-9]+$"))
+				return;
+			if (Integer.parseInt(text) <= 0)
+				return;
+
+			selectedCustomer.purchase(Integer.parseInt(textField.getText()));
 			historiesListModel.removeAllElements();
 			historiesListModel.addAll(selectedCustomer.getHistory());
 		}
 	}
-
 }