Alternator wiring issues

Hello I'm new to the site. I was wondering if anyone could help me with the fallowing issue I'm having: I bought my first z (83 280zx) last month and the alternator was overcharging. I went and got a new one, and I tested it before installing it on the car, and it was good. Now for some reason I think somehow put thenwires on wrong. There is a white cable wich is the positive, and off that there's a thinner one. That thinner one runs to a little cylinder like thing wich is grounded to the alternator.Then the is a harness wich has two wires on it. As soon as I started the car smoke came from this conector and it melted ... Can anyone assist me with any info, I would greatly appriciate it.