Multiple user Authentication

Does anyone know of any tutorials or blogs that can explain how to create Authentication for multiple users (e.g. User and Admin logins)

What you are looking for is user roles. In the tutorial [Securing your app with Spring Security]
(https://vaadin.com/learn/tutorials/securing-your-app-with-spring-security/fine-grained-access-control), there is mention of how to secure certain views to only be accessible by users with a certain role.