How to add a background image in pygame

Pygame can use the pygame.image module to add background images as follows:

1. Use pygame.image.load() to load images;
2. Use pygame.transform.scale() to scale the image;
3. Use pygame.display.set_mode() to create a new display window;
4. Use pygame.display.get_surface() to get the window surface;
5. Use pygame.display.update() to update the window surface;
6. Use pygame.display.blit() to draw the background image to the window surface.