
I want to create logins & users for my c#.net winforms application which uses
I'm changing my whole answer. I really think it's not a good idea to grant uses direct login access to your db. The DB is not the right "choke point" for permissions. Create one user with the total db permissions you will need. Then grant the users features in your application based on their role in the application (tracked in a table in your database).
There are a lot of problems with creating 1 login per user in your database. A few are 1. Maintainance nightmare 2. Now your users can log in to your db directly if they can get connected to it with Management studio or some other tool.