Script Summary: When you click on the Report Abuse link in Yahoo Answers, it will automatically report that question/answer as spam.
If the question is spam, click on the Report Abuse link next to the question.
If an answer is spam, click on the Report Abuse link next to the answer.
This will automatically submit a spam report. You don't have to do anything else. It's that simple!
This is exactly the same as if you were on the Report Abuse page, selected the I think this question violates the community guidelines radio button, typed "spam" in the Additional Details textarea, and clicked the Report Abuse button.