Just follow High level multiplayer and you will achieve what you want. Good luck, you will have a lot to work on and it's not going to be worth it after all.
You can create LAN server that will be hosted by one player. So just follow this tutorial about High level multiplayer and you should be fine.
But that means you and your friends have to be connected to the same network otherwise you won't be able to connect to host.
There is another option that requires Master Server where you will be connecting to and where netcode will be managed. That will require separated machine (dedicated server or VPS) where you can run your server. Even if that's the best option of all, it's not recommended because you will have to rewrite networking code of GoDot engine and write separated software that will be headless. Headless GoDot export is added as a new feature in 3.2 (issue) but that will take a year or more before coming out.