First, I'm really sorry if this has been posted before, but I've skimmed trough the forum and it doesn't seem to be one. Again, sorry if it is.

About a year ago i started on a pet project of turning an entire minecraft map into a giant city, adding bits and pieces over time. Now i just started playing with a mate of mine, and rather that we start from scratch, we would prefer to use my original file. I've searched far and wide, to no avail. So if anyone can explain how this works or at least point me to a link that helps, i would really appreciate it. Cheers.