ATL actually refers to them as concourses, rather than terminals, but it really doesn't matter one way or another.

Honestly, I'd say you'll probably cause yourself undue stress by printing out an airport map and trying to trace your path. For as large as it is, ATL is incredibly well-signed, and there are flight monitor screens all over the place. Just follow the signs and you'll make it to your gate in no time.

You will very likely have to change concourses; it's possible for a domestic flight to arrive into E or F, but it's not common, so you'll have to take the train or walk the long hallway next to the train (I like to walk it, but only if I have time to kill between flights). The train is located underground at the middle of each of the long concourse hallways, and it's very easy to find (you'll see a series of escalators heading down from the concourse).

Taking the train between concourses is no big deal, though - again, just follow the signs.