Offense Offsides

[BobGP383]

I am just starting to officiate football games. I am currently taking the NFHS certification course. On weekends I am helping officiate youth league football with a state certified official to get the hang of things. Ok, here is the situation. In yesterdays game the offense lined up off sides, the ball was snapped and I blew the whistle to stop play. The certified official tells me that offensive offside is a live ball foul and to jus throw the flag and not blow the whistle. I thought that any NZ infraction was a deadball foul and play was stopped? By the way, we play by High School rules. Who was correct in this case?