here is a link for Karma Police. I dont know the song so i couldnt test the chords for you. Hope you can play chords if not id recommend to play something popular classic first. For example "La valse D'Amelie" from the fabulous world of Amelie. You can find it and more
here . But you can also find out the chords yourself or well i do it like that, that if i have a melody in my head i go to the piano and just play the song cos after a while you know which chords go together. Dunno if that was helpful.... Good luck