Sylla played two years ago at Our Savior New American school in Centereach, New York. There was also some interest from Georgetown as well as some inquiries from St John's, Pittsburgh. However, Sylla did not set up any visits nor was he been offered a scholarship by these schools.
When playing for Our Savior New American, Sylla was an outstanding player. He had a solid medium-range perimeter game. Oumar was also big enough to take the ball to the basket and did his fair share of hard work in the rebounding department. Sylla also often drew the opponent's toughest offensive player and many times Oumar was successful on that end of the game too.