Yogi is right.
Suffer from this myself. After trying to correct the issue for numerous years, I have managed to minimise the winging. I have achieved this through various corrective exercises and learning to retract and depress my scapula.
Try to get your hands on a copy of NASMs Corrective Exercise book. Failing that just follow their corrective exercise continuum:
Activate- Mid/lower Traps and Rhomboids
Hope this helps, ask anymore questions if needed.