Easiest way I have found.
Save the image to your computer where you can find it - 'My pictures' eg
Then this is from Buenchico,one of our tech guides.
If you need more detailed instructions, here goes:
Go here:
http://upl.co/
Click the green button.
Navigate to the location of the image file on your computer.
Double-click on the file.
When you see a thumbnail of the image, left-click in the 'Direct link' field, to highlight the link.
Then right-click and select 'Copy'
In an AB post, right-click where you want the link to appear and select 'Paste'. (It's best to put the link on a separate line to anything else).