Create New Database user to login to SQL Server Management Studio Please see the T-SQL below:

create database db;
go

use [db]

create login [standard] with password ='dkdkdkqajHGgbh56'
CREATE USER [standard] FROM LOGIN [standard];

exec sp_addrolemember 'db_owner', 'standard'


After running this I try to login to SQL Server Management Studio as standard and I am prompted with this error: 


  login failed for user: standard


What am I doing wrong?

PS: I cannot even login as sa. I have enabled 'SQL Server Windows Authentication mode'. I am a developer (not a DBA) trying to setup a local instance of SQL Server.
I had to enable: 'SQL Server and Windows Authentication Mode', then restart the SQL Server 2012 service.