Here is a link to Google+ App. I have the Google+ App on my phone and Auto Upload chosen along with having my phone set to sync with Google+.
http://www.google.com/+/learnmore/photos/
I am pretty sure that when I set up my My Cloud, cloud access for my phone apps, that is when I was able to choose my Google+ account to auto upload them to My Cloud.
Posted by,
cat0w (USA)