Here is Ms. Ford's Screenwriting lecture.
November is National Novel Writing Month. Join the NaNoWriMo community!
Challenge yourself to the constraints of traditional poetic forms! Here are a few to get you started. Don't be insulted by the "for kids" tag--some of these are truly challenging!
The New York Times often calls for submissions from high school students. You can check this page to see what opportunities are currently available.
Looking for inspiration? Here are some short fiction pieces from the New Yorker.