Adding a downloaded singleplayer world into server

I want to add a map I downloaded to my server but I want to keep my overworld. How do I do that, I have tried to upload it throught ftp and that didnt world. (knowing I have multiverse). I also tried to make a multiverse world and delete all contents of world folder and replace them with the map I downloaded and tried to tp to it and it made no difference please help...

 

Upload the world to the root directory, then do /mv import <worldname> NORMAL if it is a normal "overworld" map.

Do the following:

Stop your server.
Upload the map
Start your server.
When it's fully started, run the above command
Stop the server again.
Go in to your server files.
Go to the logs folder.
Open the file called latest.log.
Copy and paste the contents at http://pastebin.com/.
Post it there and then link the URL here.