Agh, I haven't played that in forever, but I think. I think that you either need to get surf, which is always in the safari zone. Go to the radio tower which is right outside cerulean city. Talk to the guy by the generator and so so on (:
In pokemon Silver, the pokeflute has become a radio station on the PokeGear. Just flip the dial around until you find it. Be sure you are right near Snorlax. And don't forget to save before you fight it.