Most of league players want to become a professional streamers and gain money from their videos. They have seen some Twitch stars like "Hi im gosu" "Trick2g" or "Box Box" and they wanna copy it. Here you can learn how.
Well, the first step of this long way its to start streaming. You may create an account at Twitch and download any stream program.
I recommend you OBS. It's a really easy way to start, and it doesn't have any complication. It is also available for windows, mac and linux.
As easy as introduce your stream key and start streaming. Now you "only" have to became famous.
Good luck and I hope you can make it.
Thanks for reading.