Ensure you have the latest View Client installed on your local machine and then from the Demo Portal Landing Page click on link Launch Horizon View App

When prompted by View Client, enter your EUC Demo account credentials, Username (ensure you have @vmwdemo.com appended to username) and Password is correctly entered as was issued to you and then hit Login

There are three desktop pools available which are RDS (Windows 2012), Windows 7, and Windows 8. Double click on the desktop pool you would like to launch.

In the example below, a Win7 desktop has been launched from Horizon Client for Mac