Attaching and Detaching a Database

When I attach the Northwind database (using sp_attach_db) to SQL Server 2005, it succeeds. but when i run this request

SELECT FT_TBL.Description, 
   FT_TBL.CategoryName, 
   KEY_TBL.RANK
FROM Categories AS FT_TBL INNER JOIN
   CONTAINSTABLE (Categories, Description, 
      '("sweet and savory" NEAR sauces) OR
      ("sweet and savory" NEAR candies)'
      , 10
   ) AS KEY_TBL
   ON FT_TBL.CategoryID = KEY_TBL.[KEY]

      

        
        
        
      

    

he gives me this error

"You cannot use the CONTAINS or FREETEXT predicate in a table or indexed Category view because it is not fully indexed."

What would be the possible solution? Do I need to create a FullText index?

please help me in advance