Login to the Tessell environment.

Go to DB Services, and then My Services.

From the My Services page, click the name of the DB instance that you want to modify.

On the Overview tab of the DB Instance settings page, Under the Connection Details, Click the edit icon next to where the Host is displayed.

Enter the new DNS name that you would like to use and click Save.

You should see a message at the top of the screen that the DNS name has been successfully updated.

You should now see the new DNS name reflected in the Host properties under Connection Details