First, this doesn't really fit in the tutorials and engines section, it should be in the main programming section.
Second, I'm not sure what you mean by exchanging. If you want to, in game, change all the tiles to be tiles of the same position on a different background, it's quite a task to do. Considering what you'd have to do, it's basically impossible. You'd need to go through every individual tile and find out its properties, and then create a new tile in its place, and delete the original. Trust me, you need to think of a better way of achieving what you want.
