angularjs and spring security

[gautham vijay]

hi guys i am new to angularjs , can anyone help me in authentication process in angularjs . i am not able to understand the concept . i am trying to implement using the following link
https://spring.io/guides/tutorials/spring-security-and-angular-js/

i am not abe to get how authentication works here.. can some one pls help me with it ... thanks a ton in advance