I have no Idea how to even start this. From the other threads I know its something to to with the 'incorrect' line in the html code, but unlike the first two its not obvious (to me).
It has nothing to do with the message it displays stating your answer was wrong. It displays that on every challenge when you submit a wrong answer.
You should look into different ways websites determine whether or not you are authorized to view a page. Read about ways to store a user's login data.
by the way, google searching for this ^ will be difficult , but stay put and you will find the appropriate result.
try a very catchy technical name that starts with c