Serpentine belt

This should be the diagram for both belts. The red and orange circled nuts are just loosened. The blue arrows point at the bolts used to loosen or tighten the tensioner assemblies to adjust the belts. They want you to use a tension gauge to set the belt tension but if you don't have one you can just adjust them so they only deflect about 1/4 inch on the long run at the bottom of the belts. That will get you close. Don't over tighten as that can damage the various bearings due to excessive side loads.