background image in java form

This is my java code.What I'm trying to do is,keep the image as background and keep the buttons on top.But the image overwrites my base form.I'm only a beginner.so please help me.

Code java:

---

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
import javax.swing.*;
class petbegin extends JPanel
{
  JLabel title;
  JLabel caption;
  JButton chief;
  JButton vet;
  JButton recept;
  public petbegin()
  {
    setLayout(null);
    title=new JLabel("A VET'S PET");
    caption=new JLabel("Nothing but the best for your pet!");
    chief=new JButton("Chief Doctor's Login");
    vet=new JButton("Assistant Vets' Login");
    recept=new JButton("Receptionist's Login");
    Font f1=new Font("Castellar",Font.BOLD,28);
    Font f=new Font("Castellar",Font.BOLD,32);
    Font f2=new Font("Calibri",Font.BOLD,20);
    title.setFont(f);
    caption.setFont(f1);
    chief.setFont(f2);
    vet.setFont(f2);
    recept.setFont(f2);
 
    add(title);
    add(caption);
    add(chief);
    add(vet);
    add(recept);
    title.setBounds(335,100,500,40);
    caption.setBounds(155,180,900,30);
    chief.setBounds(285,290,300,30);
    vet.setBounds(260,370,350,30);
    recept.setBounds(285,450,300,30);
 
   }
  }
  class imageframe extends JPanel
  {
    Image img=new ImageIcon("welcome.jpg").getImage();
 
 
    public void paintComponent(Graphics g)
  {
   g.drawImage(img,0,0,this);
  }
 }
  class space extends JPanel
 
  {
 
 
  }
 
 
 
  class welcome extends JFrame
  {
 
    public static void main(String args[])
    {
      JPanel spc=new space();
      spc.setLayout(new OverlayLayout(spc));
      spc.add(new imageframe(),BorderLayout.CENTER);
 
 
        spc.add(new petbegin(),BorderLayout.CENTER);
 
        welcome t=new welcome();
        t.setContentPane(spc);
        t.setVisible(true);
        t.setSize(1000,650);
  }
 }

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Please edit your post and wrap your code with
[code=java]
<YOUR CODE HERE>
[/code]
to get highlighting and preserve formatting.

Be sure the code has proper formatting with indentations showing logic nesting levels.

yeah done editing.Thanks for telling me,I'm new to this forum!