You must begin as your own advocate, which means reading the magazines publishing the kind of stuff you write. You should also pick up the writers’ journals and buy a copy of Writer’s Market, the most valuable of tools for the writer new to the marketplace. If you’re really poor, ask someone to give it to you for Christmas. Both the mags and WM (it’s a whopper of a volume, but reasonably priced) list book and magazine publishers, and include thumbnail descriptions of the sort of stories each market uses. You’ll also find the most salable lengths and the names of editorial staffs.