His first visit to a football stadium was at Anfield, when he witnessed Liverpool defeat Manchester United 2-0 in the 1982-83 season. Harper was a student at Easington Comprehensive School. He got accepted to Liverpool John Moores University. Newcastle United recruited him from his hometown club, Seaham Red Star, for a small amount in 1993. He spent two seasons there before moving back to Liverpool to play for them. In 1996, he moved on again, this time to Vancouver Whitecaps of the US Major League Soccer (MLS) league. Harper returned to England in 1998 when he signed with Leeds United. But after one season there, he returned to Scotland when he joined Hibernian. After one season there, he returned to England for a third time when he signed with Sunderland in 2001. However, he was only with the Black Cats for one season before being traded to Canadian team Ottawa Senators. At the end of the 2002-03 season, he decided to retire from playing soccer and look for another job. During his time at Seaham Red Star and Liverpool, he learned to love the sport and wanted to become a professional player. However, due to financial difficulties, he had to quit school and work full time as a deck hand to support himself and his family. This is why he has never played any other sports besides soccer. He made his debut for Liverpool against Norwich City on August 31, 1991.