How to make a tv show for discovery channel?

id like to know how tv shows are made at discoverychannel, how all that works, for example if i go to africa and make a documental about the lions then i just go to the station and sale it? or another example, my favorite show,, mythbusters,, who came up with the idea? how much you think they can earn? imean adam and jamie the hosts,, if some one knows tell me please,,, thanks