I added A and AAA record from AWS Lightsail on Cloudflare, how do I get Wordpress running on Lightsail?

If you've already launched a Lightsail instance running WordPress, refer to this guide for assistance: https://lightsail.aws.amazon.com/ls/docs/en_us/articles/getting-started-with-wordpress-and-lightsail. Replace the <PublicIP> mentioned in the guide with your domain name.

If you're starting from scratch, or if you would like to learn more details configuring DNS, I would highly recommend consulting the following resource: https://aws.amazon.com/getting-started/hands-on/launch-a-wordpress-website/