It depends, what type of game are you talking about?
I'm going to take a wild guess and say some sort of RPG so can't say much about that. I would assume the writers write the story, dialogue trees, ect as well as provide the setting. The designers and artist would create the spaces. For other games, typically, the writing is up to Creative Director I believe.
Also, if this is you, well, take some rhetoric and grammar classes first?
Besides that, it sounds like you're almost wanting to do a mod. If that's the case, don't just jump right in and start your own team. Join an established team and just learn the process. It sounds like you know absolutely nothing about the process and you're just going to count on others to know what to do and no matter how awesome your ideas are, your project will fail.
If you're not looking to do some sort of mod project and making your own indie studio, heaven help you because that is going to go down in flames even harder than the mod project. I'm not trying to be an ass here, I'm just saying making your own game is a lot more difficult than just coming up with a good idea.
