- Inside your SE game, create a single player world using settings/mods you want on the map.
- Generate it, and then quit once the game starts.
- Type %appdata% into your explorer window and navigate to \Space Engineers\Saves - Look for the folder with the name of your world.
- Connect to FTP using Filezilla. See here: How to connect to FTP
- On the server browser, navigate to \Worlds\Saves\ and upload the folder you found earlier into that folder.
- Go onto your control panel and into your configuration editor to double check your server name is named the same as your world.