I am a single, and I have one kid. This year would be my first time claiming taxes, and I want to claim him. How do I correctly fill out a W4 form?

I have never claimed taxes before. This is my first real job (I am 19) and my son will still be under 1 by the time I claim taxes. On my w2 form, I put 0. Should I have put 1? And how can I fill out my w4 form correctly?