He should contact the vita records of the State he is in if he is in the US and request a copy of the non Identifying information document. He should also register with all of the adoption registries attached to his state of birth and known places where his parents may have lived. (Sometimes adoptees know something and sometimes they don't about locations).
He should make a list of what he knows, another of what he suspects. Sometimes the suspicions pan out and sometimes they don't.
As an Adoption Angel we use a variety of tools depending on what we find out from the adoptee.
There is a waiting list right now and the Adoption Angel Project is always looking for people to join us in helping adoptees find out about their biological heritage.
If you would like to become an Adoption Angel please answer this thread in G2G. We do have Angel Mentors who will help you learn how to help adoptees and some of us work in specific geographic areas while others tackle projects from all over the world.
thread to volunteer to be an Adoption Angel
What Adoption Angels do and don't do.
Because dealing with adoptions generally means tracking down living people, confidentiality is a big part of being an Adoption Angel.