What did they do if they found a possible target?

The first thing the officer of the deck (OOD) would do would be to order a course to point the submarine at the target. Then the OOD would immediately alert the captain. Once the boat was pointed at the target, the captain could determine which way it was moving relative to the boat. He then determined what course to take to get in front of the target to be able to attack.  When the target could be identified clearly, the captain could then confirm that it was a legitimate target

If there were other boats nearby, the captain would, ideally, alert those other submarines in the area. This was particularly true if his boat was part of a wolfpack or if he had found a convoy or part of the Japanese fleet.

At some point, if there was a chance of getting close enough for an attack, the captain would call for the tracking party. It would help provide confirmation of the captain’s estimates and allows him to make needed adjustments. Eventually, if it appeared that the submarine could get within firing range of the target, the captain would call the full crew to battle stations and attack.