The climax of the story is when Anna went to Atlanta with Marnie to visit her friends. Anna had fun adventures with Marnie and realized how much she loved and cared for her. Anna discovered that her life was more full than she knew and that she truly found herself on that trip.
The resolution is when Anna and her friends perform at the talent show. She finally had the realization that her life was full. Anna had caring new friends, a loving family who is healthy and supportive and she realized what happiness felt like.