import pygame,sys
pygame.init()
screen = pygame.display.set_mode([640,480])
screen.fill([255,255,255])
my_ball = pygame.image.load('beach_ball.png')
x = 50
y = 50
z = 10
running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
    pygame.time.delay(20)
    pygame.draw.rect(screen,[255,255,255],[x,y,90,90],0)
    x = x+z
    if x>screen.get_width()-90 or x<0:
        z = -z
    screen.blit(my_ball,[x,y])
    pygame.display.flip()
pygame.quit()