How do I provide a config file (.env) when starting a container?

I'm trying to install a GUI on Bitcoin Lightning Network Testnet. I have 2 lightning nodes running and connected together. Both in containers.

Now I would like to have a GUI interface to manage my nodes. I used this image: https://hub.docker.com/r/apotdevin/thunderhub

I can start the container and access it on my local computer on port 3000.

My question is how do I configure Thunderhub to connect to my nodes ?

If I follow the instructions on the Thunderhub home page, they refer me to this page:

https://docs.thunderhub.io/setup/#server-accounts

But the instructions are:

How should I proceed from there ? Does it means I must rebuild the image ? How do I provide a '.env' config file when starting a container

Answer

From https://docs.docker.com/engine/reference/commandline/run/#options "--env-file Read in a file of environment variables" How Did you run your thunderhub?