Puttygen SSH server refused our key

Hello - I am a newbie setting up my Wowza/Amazon EC2 instance for the first time.

I currently have an Instance that is confirmed by the command > ec2-describe-instances -region us-east-1

From which I got the following public address:

I have also executed >ec2-authorize -region us-east-1 -p22

Referring to the PDF UserGuide, from putty.exe, enter the public domain name, select SSH and Port 22. In the sidebar, click Connection: SSH: Auth

Then BROWSE for the wowza-keypair-putty.ppk file from the selection box.

Click OPEN to start a new SSH session.

Login prompt:

When I logged in as root, the server returned "Disconnected, No supported authentication methods available. Server refused our key."