You upload them under MY GOO - Click on Photos on the left under your picture - then click on + add photos at the upper right of the window. Once they are in your photo gallery, you click on your photo to make it bigger, then right click and chose properties and look for the HTTP:// link. Highlight it and copy it. Now you can use the photo button that is listed at the top of the reply box here and paste your HTTP link in where it says.
Unless I missed something, this is the only way I am aware of myself.