Careful not to put an ec2 host IP address directly in your DNS provider. Given the caching in DNS, if/when you change EC2 instances you'll be given a new IP, and your site will be down (or looking at the old server) while DNS updates.

Better to use amazon's Elastic IP. Simply 1) create one, 2) assign it to the EC2 instance of your choice, 3) add the Elastic IP as your A record as the parent post suggests.