I see requests quite often for basic info about WW2 vets, these links should help.
If you know the vet's full name and/or Army Serial Number, run it through these sites:
http://wwii-enlistment.com/ This site also allows for searches by laundry number, which is the first letter of the last name and last 4 digits of the serial number (i.e. M1234).
NARA will give you the birth year, to find out more, search by name and birth year here:
Also, Google is handy if you search using quotes such as "John Q Smith", but many online military rosters are transcribed just as the military would have done it, last name first, so try "Smith, John Q" also. If you know where the vet was from or where they died, you can add a state to the search such as ["Smith, John Q" and Michigan] in the search bar.
There are also sites you have to pay for such as ancestry.com, fold3.com, and newspapers.com that may have info, people here are happy to assist you.
Hope this helps!