Let's look at the fin pivot method for establishing neutral buoyancy. This method guides you in getting the feel of neutral buoyancy. You'll practice doing this several times in the course, using both your low pressure inflator and your oral inflator. When you use your low pressure inflator, remember to add air in short bursts. Don't hold the button down continuously, and release air from your BCD in small amounts, too.
Basically, here's how you fin pivot: 

1) lie face down on the bottom, 

2) breathe slowly and deeply and 

3) add air in small amounts to your BCD (or dry suit - your instructor will give you more ,detail on this if you'll be using a dry suit), gradually increasing your buoyancy until you slowly pivot upward on.

Your fin tips as you inhale (buoyancy increasing with lung volume), and slowly pivot downward as you exhale (buoyancy decreasing with lung volume). This means you're neutrally buoyant at that depth and can fine tune your buoyancy by controlling your lung volume. Be sure you don't hold your breath at any time.

If you have a physical challenge that makes it difficult to pivot on your fin tips, you can use your knees or another contact point for pivoting. However, use your fin tips if you can because it puts all your body mass on.