Belly: Place your hand on your gut and inhale deeply. Make sure you feel the air go into your belly; expand your stomach. As you breathe in, you'll see your hand expand. Breathe out. After several times, that uneasy feeling in your stomach should dissipate.
Chest: Put your hands on your chest and inhale deeply. While your chest expands, keep your stomach flat.
Shoulders: Breathe into your upper chest. Place your arms above your sternum and as you inhale, you'll feel your shoulders go up and down. After a few minutes, the tension should dissipate.