My wish is to create a League of Legends champion that I want. I'd like to know how to create a champion and send it to Riot. I'd also like a link to the policy of the creator system, if one exists. Thank you for your knowledge.
If you referred 10.000 friends to League of Legends until April 25th 2012 you were able to fly to Riot Games HQ and design a champion with them.
Source: RaF Design a Champ
However this was removed and now there is no official way to suggest Riot Games Champions you "invented", except for the forum.
In the forums you can post under the Champion/Item Feedback section your ideas and hope that it will get lots of upvotes, so a Riot employee looks at it, but it is very unlikely that a community-created champion sees the light of Summoner's Rift.