I need help replacing the alternator.

So my car has been dying multiple times within the past two weeks and after charging my battery twice I have come to the conclusion that I need a new alternator. I have a brand new battery too. I drive a 99 infiniti qx4. I took the battery out and I see where the alternator is and the belt. On another website it said that I need to loosen the belt tensioner pulley and I have no idea where that is or what it looks like. Another issue is that I really don't know what I'm doing and the only tools I have is one of those adjustable wrenches and needle nose pliers. And a lot of the bolts are extremely rusted. I would take my car to a shop to have them do it but they would charge more in labor than the car is probably worth. If someone could give me detailed instructions and diagrams that would be much appreciated.