You can use different syntax to achieve different things. If it is windows authentication you want, you could try this:
sqlcmd /S /d -E
If you want to use SQL Server authentication you could try this:
sqlcmd /S /d -U -P
Definitions:
/S = the servername/instance name. Example: Pete's Laptop/SQLSERV
/d = the database name. Example: Botlek1
-E = Windows authentication.
-U = SQL Server authentication/user. Example: Pete
-P = password that belongs to the user. Example: 1234
Hope this helps!