STYLETHREAD -- LET'S TALK SHOP!

You should be able to just right click on the picture, select copy, come over to ST and right click where you want the pic to go and select paste.

you cannot copy and paste pictures saved to your computer - they need to be hosted somewhere on the web. 

I load my computer saved pictures onto shutterfly.com, then once the picture is hosted there, I display it in a slide show on shutterfly, right-click on the picture and select copy, come to the ST post and click in the text field, right click again, and select paste.