To access the console of your virtual server, select either vApps, the desired vApp, then click the label of the virtual server, or select Virtual Servers and click the label of the desired virtual server.
From the menu at the top, hover over the Console drop down and select either MKS or VMRC.
MKS is an in-browser, platform agnostic console viewer, which should work in most cases.
VMRC is the vmware remote console protocol - the plugin for this has been deprecated in current browser versions, so will only work on an old browser version or once vmware releases an updated plugin.
You can send Ctrl, Alt + Delete to the virtual machine using the button at the top of the console window.
If your connection is interrupted for any reason, you can Re-connect using the button at the top of the console. This will only work while your existing login session is active.