Uber page stretch.
when making a post, if you look below the text box you can click what is called "Additional Options..." and there will be another text field labeled "Attach"
hit browse and select your screen-shot, then hit 'Post'; and so long as the picture is under 512kb (if its too high converting the picture to jpg usually helps) it will appear as a small thumb that can be enlarged by the viewer.
like the below example.
Ontopic: bathroom randomly reminds me of portal.