talk to people in the goldenrod radio tower
You add it to your Pokedex
You go to your pokegear to use it. (radio) It installs itself.
To upgrade your radio in Pokémon Gold, go to the radio tower in Lavender Town. There you will be given the radio card.
fix the power plant
you need the radio card from golden rod city in the radio tower. talk to the 2nd lady behind the counter and answer her qustions right.
You don't actually get it. When you get the Kanto radio card you turn on the radio and move the signal to the top middle.
you fix the power plant then go to the radio station talk to the guy and he gives you it
it is not a flute it is in your radio.
In Lavender Town, Pokemon Tower If you got the radio card from Goldenrod then I beleive somebody on the ground floor will give you the expansion
in the undergroud tunnel
The expn card automatically attaches to your radio now you can tune into kanto radio!
If your talkin about heart gold/ soul silver, you have to go to the radio tower in goldenrod city and take a quiz where Whitney is.