The article discusses how to setup MySQL Replication between two Amazon EC2 instances. It walks you though setting up replication for an empty database server. Adding a slave to a server already full of data is a different article.
It is assumed that you already know the basics of starting EC2 instances, connecting to them via SSH and editing files in Linux using vi/vim etc. For this tutorial, I am using the Amazon built machine image ami-2b5fba42 which is Fedora 8 base image.