Make sure yo umail your self your idea and leave the envelope sealed. That will serve as proof of when you had your idea in case anyone tries to make it theirs.
Get an artist or designer to draw it out (if that is what is needed) (my dad used to be that person) and bring the whole “idea” to a manufacturer or producer of that item, such as a toy manufacturer, publisher etc. You hire a patent lawyer to submit the idea for a patent somewhere during this process and to advice you on how to make sure your idea is not stolen.
If they like your idea, they may buy it and worry about production themselves.