Go to backend folder and create an env file containing those lines :
NODE_ENV= either "production" (for ATLAS) or "development" (for local)
ATLAS_DB_USERNAME= ...
ATLAS_DB_PASSWORD= ...
ATLAS_DB_CLUSTER= ...
ATLAS_DB_NAME= ...
MONGODB_LOCAL_URI= Your local MongoDB URI
JWT_SECRET= Generate your own secret token's key for authentification middleware.
Then run in the console :
npm install
to install dependencies
nodemon server
to start the server
Go to the frontend folder and run in the console :
npm install
to install dependencies
npm start
to run the front