Running a LAN website using FreeNas with Docker jail that has Nginx running

So I have a FreeNas server and I would like to run a website on it, except I have no clue how.
I have been reading a bit on it and I know that I need Docker to achieve this.

So I was thinking to Setup Docker with Nginx and MongoDB and serve an Angular Application as a first step. Since I know how to setup nginx and MongoDB to serve an angular app, I just need to know how to do it with docker and freenas since I have no experience with either of them.

Thing is that usually when I do nginx stuff I set it up to access it from anywhere so it is public, which not what I want.
For this project I would like to have it private so it’s only accessible on the local network but still has an easy to access url. So it won’t be like or whatever.

So can someone help me/guide me in what I need to do to make this setup?

Thanks in Advance!

Source: Docker Questions