sql server grants access to specific login to database.

You can either go to the Database => Security => Users => New User menu or Security => Logins => New Login menu to add users and assign them permissions on the database. You can assertively deny permission for roles/users on any object and operation.

Please note, I'd advise generally to use the datareader and/or datawriter roles, although these do not apply to stored procedures etc. so you'd have to manage access to them manually or create a role. I would NEVER give a web access account SA privileges. I might apply dbowner to an account to debug for permission problems, but only until I'd figured out the missing permission. If I want to exclude some object, I'd also apply a specific deny permission. If I only wanted access to a few objects from many, I'd not use the in-built roles, although I might use a custom DB role or AD group.

You can also script database permissions, but the GUI is quicker and easier. Scripting is usually reserved for remore deployments.

Please note that if you use integrated (Windows AD) security, the user must be in the same or a trusted domain as the DB server.