It's not Karr's yearbook. It's Tara's (Theresa). The first part is the typical "Stay as sweet as you are" stuff with one very sarcastic statement directed at Tara's sister.
The second part is "All about poor John" and his intentions for "revenge" someday.
Thanks. Just wanted to rule out the possibility that he added the inscription after the murder to match the ransom note's SBTC etc.