If you wish to do business under a Business Name other than your own, you must register your name of choice.
If you register a name that is the same or confusingly similar to an existing name, you can be sued and/or forced to change it, so it's a good idea to conduct a name search to see if anyone else is using the business name you want.
Once you have decided on a few choices you check to see if any or all of these names are available for use. If you receive a report that indicates there are no exact matches to your name, you may proceed with the registration of your incorporated business.
You can search for business name availability with a Preliminary NUANS Search or a NUANS Search.