California Tax Refund Question.

I am wondering when tax season comes around and we have to file with our nice and shinny social security numbers. I am pretty sure we cant receive credit for taxes right? Example if I have two kids and married to a USC and we do our taxes together can we get credit for our kids? In the past before we were married she was getting credit for my son but I couldn't get credit if I filed for him and only had a TIN. So wondering what to do for the end of the year. Also hope everyone is getting a chance to start working on their credit history.