Helpful hints for the impared ....
1.) Don't press the button called "post message" until AFTER you have typed your message.
2.) When you fail at comprehending hint number 1, for instance, you meant to type something, but instead, you only summoned up a blank nothingness prior to pressing the "post message" button, you can use the "edit" feature to fix the post so that it can have content.
If you need help with the instructions I have presented to you, I'm sure someone else can break it down further for you.