import pygame

pygame.init()

white = (255,255,255)
black = (0,0,0)
red = (255,0,0)
green = (0,255,0)
blue = (0,0,255)

gameDisplay = pygame.display.set_mode((800,600))

gameDisplay.fill(blue)

Pix = pygame.PixelArray(gameDisplay)

Pix[10][10] = green


while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            quit()

    pygame.display.update()