you go to the radio station in kanto and talk you talk to him he upgrades your pokegear so then go to the pokeradio and at the top of the pokeradio is the pokeflute that's how you wake up snorlax.
well you go to your items and press pokeradio in front of the snorlax and it will wake it up and it will fight you
If your talking about the pokeflute in Pokemon soulsilver/heartgold then go to lavender town go into the tall building and you will see a man at the very up right corner and speak to him (make sure you've returned the part that the team rocket goon took in curealean gym) and he will upgrade your pokenav so you can play the pokeflute (go to the radio and move it all the way up) Hope this helps
If you have gotten the Machine Part and given it to the manager in the Power Plant, go over to the Lavender Town Radio Tower and talk to the man in the mysterious suit. He will give you the EXPN card that alows you to update the PokeGear radio to tune into the Kanto radio as well. Then, go to the Snorlax, get out your pokeradio, then slide the cursor all the way to the top. Then, the PokeFlute will play and you "talk" to the snorlax, then it'll battle you! You can catch it too! Have fun! -Chii
Assuming you've gotten 13 badges in Gold Version: Go to the Snorlax blocking the path to the south-east of Verillian City, go to the PokeRadio and tune it to "PokeFlute" once its on PokeFlute walk back up to the snorlax and click A. It should awake now and attack you. (don't forget to save before you battle, Snorlax is level 50 and a good addition to your Pokemon team) If this is not what you mean by where do you go, I'm sorry, the question was a little vague
Go to the top of the pokemon tower in lavender town and beat team rocket and then Mr. Fuji will give you the poke flute. Then use it on the snorlax and catch it.You need to save mr fuji in Pokemon tower which is only possible if you have the silph scope which is left behind by the rocket boss at the rocket game corner.You have to go through the Pokemon Tower in Lavender town. Battle all the trainers and talk to Mr. Fuji (the old guy after all the Team Rocket grunts) and he will take you to his house. Then talk to him and he will hand you the pokeflute.
after getting your badge from canalave city,go to lake valor after meeting with dawn or lucas,your rival, and prof. rowan and beat commander saturn,then go to lake veriety and battle mars.Then the galactic grunts will be gone.P.S.It takes alot longer to get to snowpoint city than any other city you've traveled to before