I don't think PyGame will handle tiling for you, or any concept of a 'background image'. If you want something to appear multiple times on the screen, you need to draw it multiple times. If you do that onto a surface that is the same size as your screen, you can then consider that the background image and blit that to the screen at the start of every frame you draw.
-- Ben Sizer -- http://mail.python.org/mailman/listinfo/python-list