You can’t go wrong with McPherson, Catton and Foote to grasp the overall picture. There are a lot of great books about specific battles. Bowers, Sears and Shaara (for historical fiction) are good.
Neil Winick’s “April 1865” is an interesting treatise about what might have happened had Lee decided to go guerrilla. Harry Turtledove’s book “The Guns of the South” is an interesting sic-fi adventure about the Civil War and RE Lee.
I am not a Ted Turner fan, but I greatly appreciate that he produced “Gettysburg” and “Gods and Generals.” Both are excellent movies.
McPherson?
Why stop there...
Howard Zinn perhaps