Once you have the Demo installed, take a look around it to familiarize yourself with the interface of eZ Platform.
To access the back office of your installation, append /ez to its path: <your_installation path>/ez. You will be prompted for the username and password, which by default are:
username: admin
password: publish
Back office interface overview
The navigation hub at the top lets you switch between eZ Platform interface (Content) and interfaces for eZ Enterprise solutions (Page and Performance), as well as the Admin Panel.
The Content mode is the part of the interface which is the main workspace of editors and users. It is responsible for creating, editing and managing content.
Page and Performance modes are available if your have an eZ Enterprise subscription. Take a look at Get Started with eZ Enterprise to learn more.
The Admin Panel lets you manage the details of your installation, including building the content model and managing permissions.
Project structure
You can also take a look at the way the project files are structured on the example of the Demo Bundle. See Structuring an eZ Platform Project for more information.