So you're planning to host your files on CDN and wondering where to get your Amazon Secret Key and the Amazon API Key! Apparently, there’s no simple way if you're not acquainted with the system. But you need these two for many of Amazon's services. In order to get this, you need to sign up for Amazon AWS Portal Developer link.
Once you are done with that, you'll get an email which will have a link to the general account front page on which you have to goto “Security Credentials Tab” (you will be asked for your password). You will see a screen similar to the one below:
Copy the Access Key ID and the Secret Access Key and use it the way you like. Hope this helps!