Some people have been wondering how to download a custom map. Well first you have to find the map you want to download and click download. Another tab should pop up and have a download button, click it then it should say Open or Save file click Open file then a file should come up with the map. Then go to where you search your computer documents and type %appdata% and then click the first suggestion. There then should be something that says Minecraft double click that and then go to Saves and double click that. So now you have two different files the custom map and your minecraft saves. Drag the custom map file into your minecraft saves file and once you transfer the file. Once you do that open Minecraft and go to Single Player, scroll to the bottom of all your single player worlds and the custom map should be there just click the map and open it up. It may take a minute or so to load but it will work most of the time some maps just don't work. Enjoy.