git - How to reference 'environment' in github action workflow?

Question

I have the environment created named "main", but the workflow below errors out: environment created:

Below is my github workflow:

name: Deploy ADf ARM    

on:
  workflow_dispatch:

environment: 
  name: main

jobs:
  build-and-deploy:
    runs-on: ubuntu-latest
    steps:

      # Checkout code
    - uses: actions/checkout@main
      ...

at present it notes the error:

The workflow is not valid. .github/workflows/deploy-adf-arm.yml (Line: 7, Col: 1): Unexpected value 'environment'

How can I reference this environment to work?