Complex sentence: He entered the Norwood, Ontario high-school in 1992, before that he attended Adam Scott C.V.I high school in Peterborough, Ontario, where he met Adam Gontier when both of them were in Grade 9.
Split into simpler sentences: He entered the Norwood, Ontario high-school in 1992. Before that, he attended Adam Scott C.V.I High School in Peterborough, Ontario, where he met Adam Gontier when both of them were in Grade 9.