CICD using Github Actions (AWS CDK) to deploy docker images (MERN stack) to AWS ECS

This is my current Github action YAML file that works for the docker to ECR part.
Need help with deployment to ECS part along with CI tests for this React, Node, Mongo project.

name: CICD
on: push
jobs:
build:
name: Build Image
runs-on: ubuntu-latest
steps:
- name: Check out code
uses: actions/checkout@v2

- name: Configure AWS credentials
uses: aws-actions/configure-aws-credentials@v1
with:
aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
aws-region: us-east-1

- name: Login to AWS ECR
id: login-ecr
uses: aws-actions/amazon-ecr-login@v1

- name: Build, tag and push frontend image to AWS ECR
env:
ECR_REGISTRY: ${{ steps.login-ecr.outputs.registry }}
ECR_REPOSITORY: frontend
IMAGE_TAG: ${{ github.sha }}
working-directory: frontend
run: |
docker build -t $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG .
docker push $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG

- name: Build, tag and push backend image to AWS ECR
env:
ECR_REGISTRY: ${{ steps.login-ecr.outputs.registry }}
ECR_REPOSITORY: backend
IMAGE_TAG: ${{ github.sha }}
working-directory: backend
run: |
docker build -t $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG .
docker push $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG