Rear Fly

The reverse fly is a great way to target the 'posture' muscles of the upper back, including the rhomboids, the trapezius muscles and even the rear shoulders. Because you're bent over, you'll likely need lighter weights than for other back exercises. Keep in mind that the range of motion on this is small as well - you only want to lift to shoulder level rather than straining to pull the elbows up behind the torso.

1. Use light-medium dumbbells and begin in a seated position, bent over with arms hanging down and weights under the knees.
2. Try not to collapse on the legs but, instead, keep the back straight and the abs engaged.
3. Lift the arms out to the sides, up to shoulder level, squeezing shoulder blades together.
4. Keep the elbows slightly bent and only lift to shoulders.
5. Lower and repeat for 1 to 3 sets of 12-16 repetitions, with a 20-30 second rest between sets.
6. 
   

http://exercise.about.com/od/strengthtrainingworkouts/ss/backexercises2_3.htm