import sys, pygame
pygame.init()

size = width, height = 320, 240
speed = [2, 2]
black = 0, 0, 0

screen = pygame.display.set_mode(size)

#ball = pygame.image.load("ball.bmp")
ball = pygame.surface.Surface((100, 100))
ball.fill(pygame.Color(0, 0, 255, 255))
ballrect = ball.get_rect()
clock = pygame.time.Clock()

while 1:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

    ballrect = ballrect.move(speed)
    if ballrect.left < 0 or ballrect.right > width:
        speed[0] = -speed[0]
    if ballrect.top < 0 or ballrect.bottom > height:
        speed[1] = -speed[1]

    screen.fill(black)
    screen.blit(ball, ballrect)
    pygame.display.flip()
    clock.tick(40)

Add simple animation example from pygame tutorial
Add simple animation example from pygame tutorial
