How do you even get to write comics?

I always seem to have this question? Now I have read alot of articals of comic book companies and how they will let you show your ideas to them. But it seems like the way Darkhorse is doing it, they want you to send in a comic not just writing. But other times its just art or a full comic. Now what if you can't draw and can't find anyone who can, but your a good writer. Are you just screwed to not write comics unless you find someone to draw it for you to submit it. Why can't they take your writing and find an artest to drew it for you at the company?