Complex sentence: In 2012 "SF Signal" won the Hugo Award for Best Fanzine which marked the first time a fanzine won in its first year of contention and the first time an electronic fanzine of this type won the award.
Split into simpler sentences: In 2012 "SF Signal" won the Hugo Award for Best Fanzine. This marked the first time a fanzine won in its first year of contention and the first time an electronic fanzine of this type won the award.