If we want to put the window in the center of the screen we can use this:
import os
os.environ['SDL_VIDEO_CENTERED'] = '1' def main():
  background_colour = (25,25,255)
  screen = pygame.display.set_mode((320,240))
  screen.fill(background_colour)  
Now if you don't need a title window, like the next image...
 
... then you need to use this source code :
  screen = pygame.display.set_mode((320,240),NOFRAME) 