What to do when you are over with saffron city gym in Pokemon fire red?

Wake up Snorlax with the Poke Flute you got at the Pokemon Tower in Lavender Town. Head back to Celadon City and go to the left, get HM FLY from the little house blocked by the bush (use HM CUT to cut the bush) then go to the Bike Path (Cycling Road), go all the way down to Fuchsia City. There your next gym awaits.