>>>Hi,
>>>
>>>I need to assign a role db_owner to a database. How do I do it in SSMS or in T-SQL?
>>>
>>>TIA.
>>
>>If you are just adding a user to a role, see..
>>
>>http://sqlserverplanet.com/security/add-user-to-role/
>
>Thank you. This helps.
>
>Just another quick question. If I need to create a user, would it be the same as what is referred to in SSMS: Security -> Logins -> New login?

Yes. In the Security item for the server (way at the bottom of object explorer tree) you create a new SQL login, set the name and password, set the default database. Then in the Security item for the particular database, you add a new user with the name you gave the login. You can set the roles for the user there.

You can also do it via command..

http://msdn.microsoft.com/en-us/library/ms189751.aspx