Its very easy. Just head onto the bridge in between Nimbasa and Driftviel. Go back and forth on your bike and you will eventually see a dark spot and here some flapping noise (If you have your sound on). If you go onto that tile, you will either get a type of wing, or a wild battle with a Ducklett. Once you have 10 or so, go to a Pokemart and pawn them. All wings, but the Beauty Wing, are worth 1500 Pokedollars. Beauty Wings are worth 100 Pokedollars because the have no effect on Pokemon. The others raise stats.