'89 240 DL 5 speed

I bought this car for myself a few weeks ago, its a bit of a fixer upper but nothing I can't deal with. This all started when the lines on the power steering rack started to leak. We replaced the lines and then while testing to make sure it would work (turning the car on, listening, turning it off, tightening or loosening the belt etc) suddenly the car wouldn't start. Turn the key & nothing. Only enough juice to power the dome light inside, no radio etc.

I took the battery to get it tested @ autozone, they said it was @ 9% capacity and they charged it for me & it came back to 100% so I got the alternator out of the car & brought it to Napa & they said it was bad so I bought a remanned one from them. We got it all hooked up and then when I turned the car on the battery/alternator light was on, and after more tinkering and starting the car it died yet again. We tested the alternator and it wasnt putting out anything with the car running. So we thought maybe the wiring was wrong? My question is what wires go to what on the alternator and what does each one do? I hope we didn't get a bad alternator... Napa's quality has gone down hill recently.

I'm not very good with electrical stuff, its my uncle that does all the work because he knows but I will try to explain what wires we have to the best of my ability. From the wiring harness there is a thick red wire, a thick blue-ish wire, a thin red wire that goes to the alternator with a white blade connector (it has a white plastic housing)and finally a thin black wire that goes to the engine. Where do these wires go and what do they do?

Also when I started the car I noticed that none of the gauges are working now. The light will come on to light up the instrument cluster but the gas & temp gauge don't move. (speedo never worked & theres no tach, just that huge clock)