Here is how to setup a custom world:
1. Download and save the world you want to use.
2. Make sure the world is in a .ZIP archive file. You can use a program, such as (this one) to do this. If you do not zip your world, it will take a longer time to upload, because all files would upload one by one.
3. Upload the .ZIP file using the “File Manager” button on the left sidebar of the Modern Hosting Game Panel, or via SFTP. If you are unfamiliar on how to do this, you can see this article here to learn how to upload files.
4. When the ZIP file has been uploaded, in the “File Manager”, click the three dots on the right of the file and click “Unarchive”. This will extract all the world files from the ZIP archive and place them in your server directory.
5. Make sure that the world folder is named
world, otherwise your server will not be able to load.
6. "Restart" your server using the button on the console page. Your new world is now ready to use.