A 4x4 Field in Pygame

[Piethon]

So know, I wanted to create the script, I've asked for in this tread.
Till know, nothing is happening, when I run the code, but I don't get an error.

import pygame
import sys

pygame.init()

  
screen = pygame.display.set_mode([500,500])
BackGround = pygame.image.load("white.png")
screen.blit(BackGround, (0,0))
pygame.display.set_caption("Pusqumbers")
pygame.display.flip()


mapDict = {}

for x in range(1, 17): #repeat 16 times
    mapDict.update({x : None}) #None means it isn't occupied
    
def can_move(x, y):
    if 0 <= x < 4 and 0 <= y < 4:
        return True
    return False
 

Thanks for your advices, with the example code, I showed above! :-)