Dump these files in the root of your project.
Create .env file from .env.example and fill in appropriately. You must also make sure that the .env file you just created is added to the projects .gitignore.
N.B. The host for your database is db not localhost.
There is a Makefile included with various commands for ease of use:
make up
make down
N.B. This must be done when switching between sites.
make pull
N.B. This only needs to be done when an image is updated.
make install
You should add any other installation scripts to this command, for example npm install. Currently this will just install any PHP dependencies.
make composer CMD="require vendor/package"
N.B. You must pass a CMD when using make composer
make bash
Sometimes you just need to have a poke around in the container!
There is also a Makefile for and operations required for the theme. This should be placed in the base of your theme.