Serpentine belt installation instructions needed

First, make sure you have the correct routing, usually there will be a sticker showing that on the radiator support.
Next locate the tensioner pulley, it is a spring loaded arm with either a square hole for the correct sized ratchet/breaker bar or it will have a bolt head you use. You need to move it away from the belt to allow the belt to loosen up. Hold it while you remove the belt from one pulley. Next remove the belt. Now follow the diagram and rout the belt around all the pulleys. Move the tensioner again and put the belt onto the same pulley you started with.
Now before you start it look close at how you have it routed and check each pulley to be sure the belt is seated properly.

https://www.2carpros.com/articles/replace-serpentine-belt