Using a default demo user name and password you will be able to navigate through the software like an administrator user. The demo website refreshes every hour with default data so you are free to make any changes you like.
A virtual appliance is one file containing a minimal operating system and server software. You can "play" this file with a free virtual machine player. When you play the virtual appliance, it starts the second operating system and server software inside the player, on top of your existing operating system. There is no need to reboot or install anything except the player. You can then connect to the web server running inside the virtual machine player with your regular web browser.
See the ICA-AtoM virtual appliance wiki page for a download link and detailed installation instructions.