In minecraft you can download maps. Have you ever wondered how people play the adventure maps that are already created? The way they do it is by downloading the map on the internet. I just learned how to do this. You would probably think this is hard, especially on a mac, but it is really really easy. I will show you how. First find the map you want to use and download it. Example:Then put the folder that you get from the download onto your desktop. (Some download into a different type of file that you just have to click and then it turns into a regular folder). After that open finder and go to your user/Library/Application Support/minecraft/saves/
How to download other peoples minecraft maps so that you can play them
After you have gone this far just drag the map file that is on you desktop into the saves file. Then open mine craft and you should have a new save that has all the things that the map you downloaded has.
If you have any questions comment and I will get back to you soon.
Here is a tutorial on how to do this by me. The link is here.