A couple of important concepts on contained database

1. Contained login is the same thing as contained user. You use the CREATE USER syntax to create a contained login (see p.85 on the book "Securing SQL Server: Protecting Your Database from Attackers"  By Denny Cherry).

2. In SQL Server 2012, no fully contained database, a database is either NONE or partially contained.

from BOL:

CREATE DATABASE database_name 

[ CONTAINMENT = { NONE | PARTIAL } ]

[ ON 

      [ PRIMARY ] <filespec> [ ,...n ] 

      [ , <filegroup> [ ,...n ] ] 

      [ LOG ON <filespec> [ ,...n ] ] 

] 

[ COLLATE collation_name ]

[ WITH  <option> [,...n ] ]

[;]

CONTAINMENT

Specifies the containment status of the database. NONE = non-contained database. PARTIAL = partially contained database.

In SQL Server 2012 the contained database feature is currently available only in a partially contained state. A partially contained database is a contained database that allows the use of uncontained features.