Actually he/she's right you must get further into the game before you can do this part.
Battle Team Rocket in Goldenrod.
radio tower
go to underground goldenrod
you get it after defeating team rocket in goldenrod lance gives it to you
After you beat them in mahogany town.
you have to beat team rocket in goldenrod city
Easy! Goldenrod Tunnel, in the north west of Goldenrod City.
After beating team rocket at there warehouse and the radio tower at goldenrod city the director of the radio tower in goldenrod city will give the silver wing to you.
Team Rocket will be at the Goldenrod Radio Station after you have defeated Pryce in Magohany Town.
You need to defeat Team Rocket in Goldenrod City.
Goldenrod.
By going into the Goldenrod Tunnel and going to the Team Rocket Grunt and then he will put you in a Team Rocket Costume.