1990 Toyota Camry Alternator wire

I'm no mechanic. The most complex repair I've ever done on my car was putting the driveshaft back on our old car, and I even screwed that up. As for our 1990 Toyota Camry, there is a wire that connects to the top of the alternator that has pretty much fried, and I'm going by the junkyard today to see if I can't pick one up for pretty cheap. My uncle suggested that I can just get part of the wire and somehow connect it to the existing wire that is still good. How would I do this? It's a large wire that is bolted down to the top of the alternator, and it goes into the side of the engine from there. Is this a good idea? Should I just go ahead and replace the alternator as well? What tools will I need?

Continued: The wire is a thick black wire with a prong on the alternator side.