The Question and Answer section for Thirteen Reasons Why is a great resource to ask questions, find answers, and discuss the novel.
What chapter are you referring to?
Hannah's rules are simple. The first is that the tapes be listened to.... the second, that they be passed onto the next person on her list. The consequences for not following the rules is that the tapes themselves will be made public by someone...
In the section Cassette Four, Side B, we learn that Clay blames himself for not taking the time to show Hannah he cared about her.