This is how you would create a livable FreeBSD instance on EC2 by hand. The smart thing to do is to automate most of these actions. But I do it this way so you can see and understand all the different techniques. I want to create FreeBSD instances in EC2 and I want some of the management benefits that come from native AWS technologies like CloudWatch. It can be done, but it takes a bit of extra work because FreeBSD isn't Linux, and AWS doesn't directly support FreeBSD.
Before we go far, we will want some things setup in AWS IAM and VPC. I assume you have already created a VPC, decided what network numbers you're going to use, created a subnet and so on. If you haven't done those basic things, you need to go do them. I also assume you've created an ssh key and uploaded it to your AWS account.