The inverted row is a good exercise for building depth in your upper back. Grab a flat bench and place it length ways in front of the smith machine.

Adjust the height of the smith machine bar so that it's around 4ft off the floor.

Position yourself with your heels on the bench and hands grasping the smith machine bar with a slightly wider than shoulder width grip.

Straighten your body out. This is the starting position.

Keeping your body straight, pull your upper body up to the bar.

Pause, and then lower yourselfback to the start position.

Repeat for desired reps.

Exercise Tips:

Position yourself so that when you pull up, the bar touches your middle chest. The bar should not be any higher/lower than that.

Keep your body straight, and don't let your mid section sag in the middle.

To increase the difficulty add some weight plates on top of your body!