hi!
you'll want to get your non identifying information from the state your adoption was finalized in. If you were adopted through an agency they would have it, also vital records is where I got mine from in california.
You can sign up with state registries, and
www.isrr.net, also getting involved in a search / support group in your area can be REALLY helpful through the searching process....
keep a journal of everything you do! it will be very helpful.
this site has the laws and addresses of all the states in the U.S. for where to write when getting started, but its kind of hard to get through, they're site map isn't the best..if you need help let me know by PM'ing me!
http://naic.acf.hhs.gov/