After Gym seven you go to the first three islands. Then, if you catch 60 Pokemon, get the National Dex, and beat the elite four, for the first time, talk to Ceilo in the one island Pokemon center, and he will give you a pass for islands 1-7. Islands 8 and 9, or Birth Island and Navel Rock, are only available through events that happened in 2005, which gave out passes to each of these islands. You need GameShark or codebreaker to get there.
On birth island you catch Deoxys, and on navel rock, lugia and ho-oh.
Whirl islands are in the johto region which is not in firered.
Explore, catch pokemon, train your pokemon.
in 4-7 islands
The only "passes" that I can recall from Pokemon FireRed are the Tri-Pass, which grants you access to Islands One, Two, and Three, and the Rainbow Pass, which grants you access to Islands One through Seven (the Sevii Islands).
seafoam islands
you cant
After getting the ruby and delivering it to celio he will let you go to islands 4-7.
The Sevii Islands(islands 4,5,6,7)
Inside Seafoam Islands.
Seafoam islands.
They don't exist.
you get articuno in seafoam islands