Celery itegration in CircleCI

Question

I want to know how celery is implemented in CircleCI? Below is my initial configuration of config.yml file.

version: 2
jobs:
  build:
    docker:
      - image: circleci/python:3.7 run
      - image: circleci/postgres:9.6.2-alpine
        environment:
          POSTGRES_USER: $POSTGRES_USER
          POSTGRES_PASSWORD: $POSTGRES_PASSWORD
          POSTGRES_DB: $POSTGRES_DB

    steps:
      - checkout
      - run:
          command: |
            python3 -m venv venv
            . venv/bin/activate
            pip install -r requirements.txt
      - run:
          name: Running tests
          command: |
            . venv/bin/activate
            cd app/
            python3 manage.py test