Follow these instructions after you have completed the above steps.
Requirements:
Set up
Run the following commands to use the latest version of the Flutter SDK from the beta channel and enable web support:
flutter channel beta
flutter upgrade
flutter config --enable-web
After enabling web support, restart your IDE. You should now see Chrome (web) and Web Server (web) in the device pulldown.
Once you've configured your environment for web support, you can create and run a web app either in the IDE or from the command line.