There should be a little icon on your camera ap that flips the camera to the side that your screen is on. Take a picture and then open a reply window on this ap. Click the upload link on the lower right. Find your selfie and upload it. I can’t do it straight from the app. I have to click the little globe at the top and do it from my web browser. Took me a bit of aggrevation to figure it out, but I did.
