1. Visit http://www.google.com/a/ and Click Sign In
2. Enter your domain name, choose to go to domain management, click go.
3. Enter your login details and sign up
4. Click on Domain Settings
5. Click Domain names sub-heading
6. Click Advanced DNS settings
7. Note your Domain name and password, then click "Sign in to DNS console".
8. Enter your domain name and password, and click Login.
9. Click "Edit" for your Host Records.
10. Edit the "www" row to contain "mysupadupa.com." (with trailing period), then click Save.
11. Finished with that part. Proceed to your SupaDupa admin and add www.example.com to your domains page and set it to be the default using the radio button to the left of the domain. Click save and you are done!