sqlcmd new login/user
Check that your SQL Server allows SQL authentication. By default it will be windows authentication only. You can check the SQL Server errorlog which will provide the login failure reason.

The message I you would see in the log in that situation would be


  Login failed for user 'FYI_DBA'. Reason: An attempt to login using SQL
  authentication failed. Server is configured for Windows authentication
  only. [CLIENT: ]


You can change the authentication type using the GUI or T-SQL