You’ll need Google Chrome for this which can be downloaded from https://www.google.com/chrome .
After installing Google Chrome, go to https://chrome.google.com/webstore/detail/nckgahadagoaajjgafhacjanaoiihapd
and click on “Add to Chrome”. Then restart Google Chrome and you should be ready to go.
If you are using Ubuntu with something other than Unity, you will get a system tray icon. If you are using Ubuntu Unity, you can forget about the tray icon and just use the icon on Google Chrome’s toolbar.