DOD has streamlined this process somewhat in recent years, what you want is a form known as DD-214, or certificate of release from active duty or discharge. It will have listed his awards and decorations, units served in, etc.
You’ll need his military service number or, social security number, dates of service, branch, etc. The DOD has a website for requesting this, as I understand it, a written request is no longer necessary?
http://www.archives.gov/veterans/military-service-records/get-service-records.html
I got mt brothers DD214 this way and only had his name, birthday and guessed at service years.