So, I haven't done this, but I noticed the small link in the bottom right corner of the site that says Submit Game. Now that's how companies get their games there. Also, this shows that you can send your games to them.

When you click it, it turns out to be a mailto: link. If you don't use an email program, just send an email to "submitgame@miniclip.com". Well, I think you should just send in a request to them and they will follow up.
You can probably find other websites that can accept user-designed games. Run a Google search. You'll find out.
Good luck. And remember, they will probably have their rules and criteria for publishing the game.
