I think you have the wrong idea on what this will do here is a site that might help you understand
http://fantasy.premierleague.com/
http://baseball.fantasysports.yahoo.com/b1
This is not a league system for running a gaming league but a fantasy league where your members will pick 1 player from each group and the winners from each group are picked automaticly and the results will be posted.
Say you want to run a F1 racing fantasy league there would be 6 to 8 groups made by the admin and you would have to choose one player from each group for your team.
Now that you have your players for your team it comes to the race this will be done by a cron job on your forum.
This will randomly pick the winners for each group and if you have picked right your score high if you have picked wrong you will score low.
Do a search on google for fantasy league systems and you will find out more about this.