Complex sentence: She attended Park City High School until 2011 when she began competing in World Cup competitions for Ski Jumping, at which time she moved to The Winter Sports School in Park City, where she graduated in November 2012.
Split into simpler sentences: She attended Park City High School until 2011, when she began competing in the Ski Jumping World Cup. During this she moved to The Winter Sports School in Park City, where she graduated in November 2012.