import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JLabel;

public class myFrame extends JFrame{
    public myFrame(){ // constructor
        super("Guess the number game");

        JLabel newLabel = new JLabel("I have a number between 0 and 1000. Can you guess my number?" + "\n" + "Please enter your first guess");
        this.add(newLabel);
        this.setVisible(true);

        JTextField textField = new JTextField(4);
        this.add(textField);
        this.setVisible(true);
    }
}

public class TestGame {
    public static void main(String[] args) {
        myFrame game = new myFrame();
        game.setVisible(true);
    }
}