For example, if you picked signup.yoursite.com as your address, just enter signup.
Congratulations! Your CNAME record is now configured to point to LaunchRock.
If you have trouble configuring your CNAME records, you can check out the IX webhsting tutorial page. Or, view a sample message to use when you contact IX webhosting for assistance.
Once you've modified your A records, it may take up to 72 hours for changes to update live.