Take a screenshot ( if you’re using a phone ) or the screen capture thing on the pc. Then go to the forums, click on reply and you will see an button at the bottom right corner. It will say “Upload” click on that and search for the file you wan’t to show. Then wait a bit and you should get a bunch of random letters. If you’re using a pc or any bigger devices than the smart phone you will see at the right side how it’s going to look like. Simply click on reply and you got the picture!