Question

How do you get to Cinnabar Islands in HeartGold? And how do I get past Snorlax?

Answer 1

To get to Cinnabar, you must Surf from Pallet Town. To get past Snorlax, go to the Power Plant and find out the problem. Go to Cerelean Gym and follow the guy that comes out. Go back to the gym, an use itemfinder to find what is hidden there. Return that item to the Power Plant. Go to the Lavender Town Radio Tower and get the item that allows you to listen to Kanto Radio. Go to the Snorlax, go to your Radio, move the tuner (the Circle) to the direct top to the Poke Flute Channel. Save before facing Snorlax and catch it.

Answer 2

To get past snorlax you must complete the power plant problem caused by Team Rocket then visit Lavender Town's Radio Tower and talk to the old man. The man gives you some extra channels on your radio. After that go to Vermillion City, go right to Digletts cave and move the tuner to the very top where you shoud tuned into a channel called PokeFlute exit your Pokegear and prepare for battle.
To get to you have to go south from Virdian city where you will find Pallet town then use surf all the way down to Cinnabar.