Got a Green Card - How to Get One for My Son

Hello,
I have few questions...
I Married with the Citizen, I got my green card few days ago, and my lawyer told me to work on my son right now (He is With ME in USA and he is 16 Years Old)
And Now...I paid him About 5000$
He sent (For my son)
i-130 and its approved
Now he told me to pay I-864 - 70$
And Immigration Visa Application Processing FEE Bill - 400$
Now i stared to read about this everything... I-130 is for somebody outside the US...
Now im without money, and i feel cheated...
What should i do to get a green card for my son?
My Wife is his step mother, and she is a sponsor.

I will much appreciate any help, i cant go to lawyer, i have no money, the old one wants a money...
Thank you ...

Did your son enter the US legally? Does he have a visa permitting him to be here?

He entered legaly, but the visa is now expired

anyone? I really need to know that