Thread: JOption to JFrame HELP...messed my program up

import java.awt.*;
import javax.swing.*;
 
import java.awt.event.*;
import java.util.Random;
import java.util.Scanner;
 
 
	public class WordGuessGame
	{
        JFrame frame;
        JPanel panel;
        JLabel label;
        JTextArea input;
        String word;
 
        JButton checkletter; 
        JButton giveup;
 
        public static void main(String[]args)
        {
                WordGuessGame app = new WordGuessGame();
                app.start();
        }
 
        public void start()
        {       
                frame = new JFrame();
                panel = new JPanel();
                frame.getContentPane().add(BorderLayout.NORTH, panel);
                frame.setVisible(true);
                frame.setSize(500,300);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                panel.setLayout(new FlowLayout());
 
 
 
                label = new JLabel(" Word Guessing Game");
                panel.add(label);
 
                checkletter = new JButton("Start");
                panel.add(checkletter);
 
 
                input = new JTextArea("");
                panel.add(input);
 
                giveup = new JButton("Give up!");
                panel.add(giveup);
 
 
 
        }
 
		//create an inner listener class for the first button 
		class startListener implements ActionListener 
		{
			String guess;
			int wrongGuess;
			Random generator = new Random();
 
			JLabel invalidLbl;
			JLabel guessedLbl;
 
			public void actionPerformed(ActionEvent event) 
			{
				//string array of words
				String [] words = {"paprika", "savvy", "knickknack", "cyclists", 
						"daydreamt", "cushion", "karaoke", "parlour", "cormac", 
						"riverrock", "storage", "chemistry", "cockatoo", "fujitsu"};
 
			char userGuess, again;//declare variables 
 
				//start do loop
				do {
 
					int num = words.length;//words that are available 
					word = selectRandomWord(words, num);//selects a random word from array
 
					int word_length = word.length();//finds length of word
					guess = initialise(word_length);//creates dashes to display depending on length of word
					wrongGuess = 0;//user wrong guesses
 
					boolean[] history = new boolean[26];//stores users guesses in array so not repeated again
					System.out.println(guess);//outsputs the current users guess
 
					//while loop to repeat the users guess until lives run out
					while(wrongGuess <10 && !guess.equals(word))
					{
						userGuess = getGuess(guess, wrongGuess);//gets the users next guess
 
 
 
						if (userGuess < 'a' || userGuess > 'z')//ensures that guess is a letter
							invalidLbl.setText(invalidLbl.getText() +("Invalid guess " + userGuess));//display output if guess is not a letter and displays what they entered
 
						else if (history[userGuess - 'a'])//checks history array to ensure guess has already not be used
							guessedLbl.setText(guessedLbl.getText() +("You already guessed " + userGuess));//display output if guess has been entered before
 
						else
						{
							history[userGuess - 'a'] = true;//enters letter as guessed to histroy array
							if(inWord(userGuess, word))	//checks if guess letter is in word and enters in to display
								guess = fillInGuess(userGuess, guess, word);//adds the guessed letter to variable
 
							else//wrong guess
								wrongGuess++;//chnages amount of wrong guesses (adds on, loses a life)	
						}
 
						//if statement which displays answer is number of wrong guesses is reached
						if(wrongGuess==10)
							JOptionPane.showMessageDialog(null, "The answer was: " + word);//output to user is maximum guesses has been reached
 
					}again=goAgain();// opens goAgain method
				} while (again=='Y');//repeats if answer to restart game is "Y"
			}//close playgame method
 
 
			//start goAgain method
			public char goAgain()
			{
				//display output to prompt user to go again, if yes do loop is repeated above
				return JOptionPane.showInputDialog("Do you want to play again?  (Y/N)").toUpperCase().charAt(0);
			}
 
			//select random word method
			public String selectRandomWord(String[] words, int num)
			{
				//selects a random word from array
				return words[generator.nextInt(num)];
			}
 
			//start initialise method
			public String initialise(int word_length)
			{
				//sets the number of "-" to be displayed depending on length of word 
				String temp="";
				for(int i=0;i<word_length;i++)
					temp+="-";
				return temp;
			}
 
			//start getGuess method
			public char getGuess(String currentGuess, int numWrong)
			{
				//output on optionpane to prompt user to enter another guess and shows how many wrong guesses made
				return JOptionPane.showInputDialog("Your current guess is " +
				currentGuess + "\n\n"+ numWrong + "/10" + " wrong guesses so far\n"
				+ "\nEnter your next guess").toLowerCase().charAt(0);
			}
 
			//start inWord method
			public boolean inWord(char userGuess, String word)
			{
				//checks if users guess is a charactor in the word 
				boolean returnvalue=false;//if not returns as false
				for(int i=0;i<word.length();i++)
					if(userGuess==word.charAt(i))
						returnvalue=true;//is yes returns as true
				return returnvalue;
			}
 
			//start method fillInGuess
			public String fillInGuess(char userGuess, String guess, String word)
			{
				//fills in the correctly guessed charactor to the position in the word to display in panel
				String temp="";
				for(int i=0;i<word.length();i++)
				{
					if(guess.charAt(i)!='-')
						temp=temp+guess.charAt(i);
					else if(word.charAt(i)!=userGuess)
						temp=temp+"-";
					else temp=temp+userGuess;
				}
				return temp;	
			}//ends fillInGuess method			
			}
 
 
 
		//end class
 
 
 
	}

Where do you add the action listener to any buttons?