This exercise is similar to the incline bench press. The smith machine acts as support/ spotter for you in this case. To do this exercise you need a incline bench. Put the incline bench below the smith machine and adjust weights according to your capacity. Now lie flat on the bench and grip the barbell symmetrically in medium grip / not too far from chest or too close just after the shoulders. Lift the barbell of the rack by turning your wrists out ward. Initially keep your wrists inward. After you turn them out it comes straight.

Now slowly lower the barbell towards your clavicle then raise it upwards. This exercise targets upper chest / upper pecs. You have to squeeze your chest at the top. Also don’t touch the barbell with chest. It will cause unnecessary stress on shoulders.
Video Demo On How to do Smith Machine Incline Bench Press

Video Demo 2