no classes are needed at all, because with writing all you need is time, a few ideas (sometimes; or a really strong emotion, or inspiration) and an audience / some critics. either way, the more you write, the better you get.
first you write the book, and then you send it to an editor / proofread it yourself (or have a friend do it), then after you're sure you've gotten out all kinks / unnecessary things, you send it to numerous publishers till they agree to publish your book.
good luck! x
ps. writing classes could help, i guess, but i don't really think there are any "writing a book" classes. just take like a creative writing class.
