Question Integrating Multiplayer Onto an Existing Weapons System?

Hi everyone,

I already have an FPS weapons system complete with player damage, but only one player can play at a time due to it's lack of networking support. I know that you can use PUN2 as networking, but I don't know how to set up servers and such while integrating an existing FPS weapons system. Any help is appreciated since I'm fairly new to unity. Tutorials and examples are appreciated also. Thanks in advance!

BTW, I'm using Unity 3D 2020.3.5f1 and am using C# for scripting.