Alright... Like I said, the IMG code is probably easier, but this is how I do it on Chrome. Forgive the crudity, I print screened and pasted :lol:
After you click the pic you want on your Photostream, click those diagonal arrows circled.
Then right click, pic your size
When you get to the screen with all the sizes, right click the picture itself (not the sizes above it) and open it in a new tab
Grab the url, then click insert image on here and paste.
Done.