Expecting a baby in Berlin after moving there from

Hi,

My name is Tatiana and I am pretty new here!
We are moving to Berlin in a week time! Very excited:)
We are also expecting a baby end of may:) my husband said that social system is so good in Germany that we will be entitled to receive Kindergeld. I was wondering if someone can help me to find out which particular documents about my income i have to provide (and to whom?) so we can sign for this?)

Would appreciate your help a lot!

Thank you