1987 Dodge 600 Belt Question

Hi,
The belt to the alternator tore on my car. When it tore, it knocked off the belt next to it, running to what I believe is the compressor. I was able to get the belt back on the water pump and alternator, but the other belt is giving me trouble. It runs down on the water pump, then some little round wheel, and then the compressor. I was looking for some sort of tensioner, but did not see any. Am I overlooking it? What do I need to do to get that belt back on? Any help you can give is greatly appreciated.