Here are a few resources to help you get started:

Website development

Get a free domain:

https://www.hostinger.com/free-domain

Free webhosting with AWS:

https://aws.amazon.com/websites/

Learn basic HTML/CSS/JS

https://www.w3schools.com/howto/howto_blog_become_frontenddev.asp

App Development

https://docs.flutter.dev/get-started/install