import pygame
import sys

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

surface = pygame.surface((50, 50))
surface.fill((0,255,0))

pos = [175, 125]

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