Create an AWS Account
Create an Instance
Choose an AMI in the classic instance wizard: I chose the Basic 64-bit Amazon Linux AMI.
Instance details: keep the default settings.
Create a new key pair. Enter a name for your key pair (i.e. christophe) and download your key pair (i.e. christophe.pem).
Select the quick start security group.
Launch your instance.
You may have to chmod your .pem file as follows:
Depending on the image you chose, you may also have to replace ec2-user with rootor ubuntu. ec2-user is what you need for an Amazon Linux AMI.