Should be pretty simple. The tensioner is on the top back of the engine bay. There is a bolt welded to the tensioner that you attach a socket/wrench too. Turn the bolt to remove tension from the belt and slide the belt off. Pay attention to the way the belt is routed and route the new one the same way. You will need to turn the tensioner again when placing the belt back on in order to get enough slack to slide it over the pulley. I recommend saving the old belt as a spare in your trunk if it isn't completely trashed (in case of emergency).
There is only one way to do it properly. The diagram should be visible when you pop the hood.