Somebody stole my idenity also use my son's social sercurity number how could I find out who was it and what address it got send to?

If you know this as FACT, then report the event to the police and let them deal with it.
That's what they get paid for after all.
There is very little that you, as a private citizen, can do.

How did they steal your identity? Did you leave a passport somewhere and someone took it?
How is your son involved in this? I know you say ss # but how did they get it ? This is information you should not be lax about and always keep close to your person at all times or locked up until you need it.

Does this involve your income tax filing ?

But you don't find out, you report it to the police and you report it to the IRS if he has to do with income taxes. If it is income taxes,you w will have to file on paper ( not online) and provide proof of ID, and it will take 6 months or more for the IRS to investigate and correct.