How to enable a user using a script?
if you want to access a database using a login you created, you need some decisions to make,
first : you have to create a user in database for the login you created, it could be a same name or a different name for it.
you also need to decide what amount of permissions you need for the login,

the sample below is for creating a login with a specific password, that is going to access adventureworks2012 with db_datareader permission over database:

USE [master] 
GO 
CREATE LOGIN [test] WITH PASSWORD=N'123', DEFAULT_DATABASE=[master], CHECK_EXPIRATION=OFF, CHECK_POLICY=OFF 
GO 
USE [AdventureWorks2012] 
GO 
CREATE USER [test] FOR LOGIN [test] 
GO 
USE [AdventureWorks2012] 
GO 
ALTER ROLE [db_datareader] ADD MEMBER [test] GO