If you don't already have the Chrome web browser on the computer, install it from google.com/chrome

From the Chrome browser, install the Chrome Remote Desktop extension - http://goo.gl/V9bJ9
On that page, click on the + Free button near the top right, and allow the extension to be installed.

Start the Remote Desktop program: copy this URL and paste it into the Chrome Location bar:

chrome-extension://gbchcmhmhahfdphkhkmpfmihenigjmpp/main.html