WWII Veteran information (he moved to America from Poland in 1929)

I recently found out that my great-grandfather was a WWII veteran, presumably after he moved to America from Poland in 1929. I have found out where he was born, his immigration date, death, social security number, and that he served in WWII. I don't know anything about his service during the war, except that he served in it. I would like to find out more about his service during the war, where could I go to help with this?

Rudy, if you give me a name i can see if I can find some info on ancestry for you, there is however a site for veterans

let me check some stuff, my uncle served in foreign war so I think for that its veterans of foreign wars.. I am not sure

but I can try to locate something for you to start with. HOPEFULLY.