maybe you have the overlay off. Press SHIFT + ALT + Z or go to the icon here. If it is blue, it is active and you should see Edges and Faces

An easy method to upload images here is also if you work with the Windows SnippingTool. You press WindowsKey+SHIFT+S then simply “frame” the area you want to screenshot and then just press CTRL+V in the text field at CGCookie to paste. At least that’s how I do it.