You'll want to read Thucydides and Xenephon who wrote very readable accounts as participants/onlookers. The landmark editions have maps and appendixes which are helpful. Plutarch's lives also cover several key figures including Pericles and Alcibiades

If this is part of a general interest in greek stuff not just history you might also want to read Lysistrata by Aristophanes. It's a comedy with the premise that Athenian and Spartan women go on sex strike to stop the war, written while the war was still raging (with Athens on the ropes after the Sicilian expedition.

Finally there are free online lectures covering the period and beyond though to be aware they come from a particular perspective and I understand not one representing modern mainstream scholarship https://oyc.yale.edu/classics/clcv-205