I am not sure I understand your question. If you are using the MS SQL designer, just choose nvarchar(50) for the data type for that column. In case you are hand-coding that still isn't an impossible task, for example:
CREATE TABLE [dbo].[Test](
[ID] [int] NOT NULL,
[Name] [nvarchar](50) NOT NULL
) ON [PRIMARY]
Pls. elaborate if this is not what you are looking for.