1) Create Online League
2) Purchase/Find Web Hosting with FTP access (Linux or Windows doesn't really matter...)
3) On the Configuration Screen, set up the following values.
Server: The FTP address of your server (example: ftp.wolverinestudios.com)
Remote Directory: The root directory you want your files saved into. (example: /nfl2/league)
Web Root: The Web Address that matches your remote directory. (example: http://nfl2.wolverinestudios.com/league)
FTP User: The FTP User name
FTP Password: The FTP Password
FTP Passive Mode: Enable Passive Mode (normally this is fine to leave as is)
The key to this is that you have to know your remote directory and the web url that corresponds. In my case I have multiple sites hosted on the same server, so I have to go to my nfl2 subdirectory for my upload. If you are only hosting one site it may be a directory called public_html or something like that, or it may just be ok to upload to the root folder with no subdirectory at all. I use /league/ so that I can keep my root level files and site from being overwritten and I suggest this for any online league.
The web url has to match this, so if you put things in a subdirectory called /league/ then your web address will most likely contain /league/.