Use Flickr
Open your chosen photo to get this screen...make sure, in the additional information, the picture is set to 'public'
Then press the curly arrow at the bottom right of the screen to get this page
Make sure you use the 'BB code' screen and select the size of pic you want
Then cut and paste the 'url' code, that you see, into your XT660 post. Or you could just drag the code across if you're using two open window pages side by side (one being the XT one and the other being Flickr)