How to replace a serpentine belt on a 2000 Chrysler cirus?

There is 2 bolts on backside of powersteering pump 13mm loosen those and the bottom 15mm bolt loosen as well take outer belt off and then loosen idler pulley adjustment screw which i believe was 13mm loosen middle bolt on idler pulley and slide back and the old belt is off. replace and make sure belt you have is same size, i didnt realize the dip**** at autozone gave me belt for the 4 cyl. dohc which looks exactly the same and is about 2 in. shorter than the one for the 6cyl2.5