Complex sentence: Ryan attended St. Mary's Catholic School in Janesville, where he played on the seventh-grade basketball team, then attended Joseph A. Craig High School, where he was elected president of his junior class, and thus became prom king.
Split into simpler sentences: Ryan attended St. Mary's Catholic School in Janesville, where he played on the seventh-grade basketball team. He attended Joseph A. Craig High School in Janesville, where he was elected president of his junior class, and thus became prom king.