I am trying to create a "map of a city" using pygame. I want to be able to put images of buildings in specific grid coords rather than just filling them in with a color.

This is how I am creating this map grid:

def clear():
    for r in range(rows):
        for c in range(rows):
            if r%3 == 1 and c%3 == 1:
                color = brown;
                grid[r][c] = 1;
            else:
                color = white;
                grid[r][c] = 0; 
            pygame.draw.rect(screen, color, [(margin+width)*c+margin, (margin+height)*r+margin, width, height])         
    pygame.display.flip();

Now how do I put images of buildings in those brown colored grids at those specific locations? I've tried some of the samples online but can't seem to get them to work. Any help is appreciated.

If anyone have a good source for free sprites that I can use for pygame, please let me know. Thanks!