import pygame
import sys
pygame.init()
screen = pygame.display.set_mode((400,300))

surface = pygame.Surface((50, 50))
surface.fill((0,225,0))


while True:
    events = pygame.event.get()
    for event in events:
        if event.type == pygame .QUIT:
            pygame.quit()
            sys.exit()
    screen.blit(surface, (175, 125))
    pygame.display.update()


import pygame
import sys

pygame.init()
screen = pygame.display.set_mode((400, 300))

surface = pygame.Surface((10, 10))
surface.fill ((0,225,0))

pos = [175, 125]

while True:
    events = pygame.event.get()
    for event in events:
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_RIGHT:
                pos[0] +=20
                screen.blit(surface,pos)
                pygame.display.update()