First, ensure that you've registered for the promotion at the Be a Better Planet site. Then go to Yahoo! Answers. You'll need to log in with your Yahoo! ID.

Each question has a 4-day "open" period during which you can post an answer.

To answer a question:

• Go to any question in the Open Questions section and click Answer this Question.
• Enter your answer in the 'Your Answer' field and include the URLs of any sources you want to reference in the Source(s) field.

Once the question is closed, either the question asker or the Answers community will select the best answer. If your answer is selected as the best, you've just scored credits in the Be a Better Planet promotion. You'll also earn the standard Answers points for your level ranking on Yahoo! Answers.

Remember, best answers in the Environment category (75 credits) score higher than best answers in other categories (10 credits).