Try a flamenco style and sing along....its a typical flamenco style chord pattern....donno the exact scale...but lets say u take A major to start - Arrey Diwano will fall on A Major... Mujhe Pehchaano will have a A# Major (or Bb Major - whateva u wanna call it), Kahaan se aaya will be a C Major and then back to A Major to wrap up the line..... play by ear and see and u`ll get it...