Atlas website. Look for information, then manuals. There are instructions, (Signal system support), for each signal piece.
Wiring is a bit different than what most would think. (Example: I installed green/red dwarf lights for each turnout). Wires were paralleled to each of the three switch motor leads. Each dwarf light had a relatively complex circuit board, that required power and then connection to the switch motor. It become more complex when you powered more than one dwarf light activated from one turnout. The original person to contact, 20 years ago, was Steve Horvath.