Updating paper version

On startup server gives warning:
You’ve not updated in a while. Please download a new build as per instructions from https://papermc.io/downloads

I am running the Java 16
Server 1.17.1
Paper version git-Paper-100

Can’t find a paper.jar to replace to update. All I can find is spigot.yml, and paper.yml

Can anyone help me figure out how to update my paper version? I am fairly inexperienced in this sort of thing, so talk to me a little like I’m in elementary school. :-p