Complex sentence: He started playing piano and then guitar in elementary school, then attended the Fiorello H. LaGuardia High School (the "Fame" School) in New York City, where he studied violin and composition.
Split into simpler sentences: He started playing piano and then guitar in elementary school. He then attended the Fiorello H. LaGuardia High School (the "Fame" School) in New York City, where he studied violin and composition.