It is presumed that you already have an AWS account. If not, navigate to this url and follow the instructions: aws.amazon.com.
The AWS account must not be an EC2-Classic account as the RDS instance will fail to launch as it presumes there is a default VPC, which does not exist in an EC2-Classic account. If you created your account after 2013-12-04, it supports EC2-VPC only and so it will work with the LANSA CloudFormation template.
These exercises instantiate Cloud services for which you may be charged. You are responsible for all such charges that you may incur.
Here is a summary of AWS services which LANSA uses written in plain English: http://www.evernote.com/l/AA3aAMHNB9RJe5XY9U1wWweMyhmvo7ZB-Zs/