flying thru ATLANTA

[pilot]

Hi everybody,
my parents are flying from VIENNA, AUSTRIA To LOS Angeles Thru ATlanta.
Their flight number from vienna to atlanta is DL041. they will land on terminal S.
they dont speak any english, so I was wondering if anybody could write me what happens right after they leave the plane (when, where do they pick up the luggage where they drop it off again, where is the immigration, customs etc.). will they have to take any airport trains? any signs for connecting flights?
the second flight leaves also from terminal S and it is also a delta flight.

I will meet them in the terminal, cause I am already in the U.S. and I want to make sure they will make it on time and wont get lost or go somewhere they are not supposed to go (for example procceed with passengers who do not have connecting flights... which would not be good)...

Thanks everybody for answers,

Tomas