The entry point of the system is the administration page. It is divided up into boxes, with a section in each box. These are configured for your application. To see this in action go to the admin page. This link will log you in as the demonstration user. It will open in a new window.
A section can have:
The login you have used will give you access to all of the functions we have configured. However other logins give more restricted access. For example: this link will log you in as a sales person (Willy Loman) so it only give access to sales related functions. This is controlled by permission sets. Each permission set controls access to home page sections, tables and even the fields in each table.